## Appendix B Summary of Library Facilities ¶

This appendix is a complete list of the facilities declared within the header files supplied with the GNU C Library. Each entry also lists the standard or other source from which each facility is derived, and tells you where in the manual you can find more information about how to use it.

`ACCOUNTING`

  `utmp.h` (SVID): Manipulating the User Accounting Database.

`AF_FILE`

  `sys/socket.h` (GNU): Address Formats.

`AF_INET`

  `sys/socket.h` (BSD): Address Formats.

`AF_INET6`

  `sys/socket.h` (IPv6 Basic API): Address Formats.

`AF_LOCAL`

  `sys/socket.h` (POSIX): Address Formats.

`AF_UNIX`

  `sys/socket.h` (BSD): Address Formats.

  `sys/socket.h` (Unix98): Address Formats.

`AF_UNSPEC`

  `sys/socket.h` (BSD): Address Formats.

`tcflag_t ALTWERASE`

  `termios.h` (BSD): Local Modes.

`int ARGP_ERR_UNKNOWN`

  `argp.h` (GNU): Argp Parser Functions.

`ARGP_HELP_BUG_ADDR`

  `argp.h` (GNU): Flags for the `argp_help` Function.

`ARGP_HELP_DOC`

  `argp.h` (GNU): Flags for the `argp_help` Function.

`ARGP_HELP_EXIT_ERR`

  `argp.h` (GNU): Flags for the `argp_help` Function.

`ARGP_HELP_EXIT_OK`

  `argp.h` (GNU): Flags for the `argp_help` Function.

`ARGP_HELP_LONG`

  `argp.h` (GNU): Flags for the `argp_help` Function.

`ARGP_HELP_LONG_ONLY`

  `argp.h` (GNU): Flags for the `argp_help` Function.

`ARGP_HELP_POST_DOC`

  `argp.h` (GNU): Flags for the `argp_help` Function.

`ARGP_HELP_PRE_DOC`

  `argp.h` (GNU): Flags for the `argp_help` Function.

`ARGP_HELP_SEE`

  `argp.h` (GNU): Flags for the `argp_help` Function.

`ARGP_HELP_SHORT_USAGE`

  `argp.h` (GNU): Flags for the `argp_help` Function.

`ARGP_HELP_STD_ERR`

  `argp.h` (GNU): Flags for the `argp_help` Function.

`ARGP_HELP_STD_HELP`

  `argp.h` (GNU): Flags for the `argp_help` Function.

`ARGP_HELP_STD_USAGE`

  `argp.h` (GNU): Flags for the `argp_help` Function.

`ARGP_HELP_USAGE`

  `argp.h` (GNU): Flags for the `argp_help` Function.

`ARGP_IN_ORDER`

  `argp.h` (GNU): Flags for `argp_parse`.

`ARGP_KEY_ARG`

  `argp.h` (GNU): Special Keys for Argp Parser Functions.

`ARGP_KEY_ARGS`

  `argp.h` (GNU): Special Keys for Argp Parser Functions.

`ARGP_KEY_END`

  `argp.h` (GNU): Special Keys for Argp Parser Functions.

`ARGP_KEY_ERROR`

  `argp.h` (GNU): Special Keys for Argp Parser Functions.

`ARGP_KEY_FINI`

  `argp.h` (GNU): Special Keys for Argp Parser Functions.

`ARGP_KEY_HELP_ARGS_DOC`

  `argp.h` (GNU): Special Keys for Argp Help Filter Functions.

`ARGP_KEY_HELP_DUP_ARGS_NOTE`

  `argp.h` (GNU): Special Keys for Argp Help Filter Functions.

`ARGP_KEY_HELP_EXTRA`

  `argp.h` (GNU): Special Keys for Argp Help Filter Functions.

`ARGP_KEY_HELP_HEADER`

  `argp.h` (GNU): Special Keys for Argp Help Filter Functions.

`ARGP_KEY_HELP_POST_DOC`

  `argp.h` (GNU): Special Keys for Argp Help Filter Functions.

`ARGP_KEY_HELP_PRE_DOC`

  `argp.h` (GNU): Special Keys for Argp Help Filter Functions.

`ARGP_KEY_INIT`

  `argp.h` (GNU): Special Keys for Argp Parser Functions.

`ARGP_KEY_NO_ARGS`

  `argp.h` (GNU): Special Keys for Argp Parser Functions.

`ARGP_KEY_SUCCESS`

  `argp.h` (GNU): Special Keys for Argp Parser Functions.

`ARGP_LONG_ONLY`

  `argp.h` (GNU): Flags for `argp_parse`.

`ARGP_NO_ARGS`

  `argp.h` (GNU): Flags for `argp_parse`.

`ARGP_NO_ERRS`

  `argp.h` (GNU): Flags for `argp_parse`.

`ARGP_NO_EXIT`

  `argp.h` (GNU): Flags for `argp_parse`.

`ARGP_NO_HELP`

  `argp.h` (GNU): Flags for `argp_parse`.

`ARGP_PARSE_ARGV0`

  `argp.h` (GNU): Flags for `argp_parse`.

`ARGP_SILENT`

  `argp.h` (GNU): Flags for `argp_parse`.

`int ARG_MAX`

  `limits.h` (POSIX.1): General Capacity Limits.

`baud_t BAUD_MAX`

  `termios.h` (GNU): Line Speed.

`int BC_BASE_MAX`

  `limits.h` (POSIX.2): Utility Program Capacity Limits.

`int BC_DIM_MAX`

  `limits.h` (POSIX.2): Utility Program Capacity Limits.

`int BC_SCALE_MAX`

  `limits.h` (POSIX.2): Utility Program Capacity Limits.

`int BC_STRING_MAX`

  `limits.h` (POSIX.2): Utility Program Capacity Limits.

`BOOT_TIME`

  `utmp.h` (SVID): Manipulating the User Accounting Database.

  `utmpx.h` (XPG4.2): XPG User Accounting Database Functions.

`tcflag_t BRKINT`

  `termios.h` (POSIX.1): Input Modes.

`int BUFSIZ`

  `stdio.h` (ISO): Controlling Which Kind of Buffering.

`tcflag_t CCTS_OFLOW`

  `termios.h` (BSD): Control Modes.

`int CHAR_BIT`

  `limits.h` (C90): Width of an Integer Type.

`CHAR_MAX`

  `limits.h` (ISO): Range of an Integer Type.

`CHAR_MIN`

  `limits.h` (ISO): Range of an Integer Type.

`CHAR_WIDTH`

  `limits.h` (ISO): Width of an Integer Type.

`int CHILD_MAX`

  `limits.h` (POSIX.1): General Capacity Limits.

`tcflag_t CIGNORE`

  `termios.h` (BSD): Control Modes.

`int CLK_TCK`

  `time.h` (POSIX.1): Processor Time Inquiry.

`tcflag_t CLOCAL`

  `termios.h` (POSIX.1): Control Modes.

`CLOCKS_PER_SEC`

  `time.h` (ISO): Processor And CPU Time.

`int CLOCKS_PER_SEC`

  `time.h` (ISO): CPU Time Inquiry.

`clockid_t CLOCK_BOOTTIME`

  `time.h` (Linux): Getting the Time.

`clockid_t CLOCK_BOOTTIME_ALARM`

  `time.h` (Linux): Getting the Time.

`clockid_t CLOCK_MONOTONIC`

  `time.h` (POSIX.1): Getting the Time.

`clockid_t CLOCK_MONOTONIC_COARSE`

  `time.h` (Linux): Getting the Time.

`clockid_t CLOCK_MONOTONIC_RAW`

  `time.h` (Linux): Getting the Time.

`clockid_t CLOCK_PROCESS_CPUTIME_ID`

  `time.h` (POSIX.1): Getting the Time.

`clockid_t CLOCK_REALTIME`

  `time.h` (POSIX.1): Getting the Time.

`clockid_t CLOCK_REALTIME_ALARM`

  `time.h` (Linux): Getting the Time.

`clockid_t CLOCK_REALTIME_COARSE`

  `time.h` (Linux): Getting the Time.

`clockid_t CLOCK_TAI`

  `time.h` (Linux): Getting the Time.

`clockid_t CLOCK_THREAD_CPUTIME_ID`

  `time.h` (POSIX.1): Getting the Time.

`int COLL_WEIGHTS_MAX`

  `limits.h` (POSIX.2): Utility Program Capacity Limits.

`cpu_set_t * CPU_ALLOC (size_t count)`

  `sched.h` (GNU): Limiting execution to certain CPUs.

`size_t CPU_ALLOC_SIZE (size_t count)`

  `sched.h` (GNU): Limiting execution to certain CPUs.

`cpu_set_t * CPU_AND (cpu_set_t *dest, cpu_set_t *src1, cpu_set_t *src2)`

  `sched.h` (GNU): Limiting execution to certain CPUs.

`void CPU_CLR (int cpu, cpu_set_t *set)`

  `sched.h` (GNU): Limiting execution to certain CPUs.

`int CPU_COUNT (const cpu_set_t *set)`

  `sched.h` (GNU): Limiting execution to certain CPUs.

`int CPU_EQUAL (cpu_set_t *src1, cpu_set_t *src2)`

  `sched.h` (GNU): Limiting execution to certain CPUs.

`void CPU_FREE (cpu_set_t *set)`

  `sched.h` (GNU): Limiting execution to certain CPUs.

`int CPU_ISSET (int cpu, const cpu_set_t *set)`

  `sched.h` (GNU): Limiting execution to certain CPUs.

`cpu_set_t * CPU_OR (cpu_set_t *dest, cpu_set_t *src1, cpu_set_t *src2)`

  `sched.h` (GNU): Limiting execution to certain CPUs.

`void CPU_SET (int cpu, cpu_set_t *set)`

  `sched.h` (GNU): Limiting execution to certain CPUs.

`int CPU_SETSIZE`

  `sched.h` (GNU): Limiting execution to certain CPUs.

`cpu_set_t * CPU_XOR (cpu_set_t *dest, cpu_set_t *src1, cpu_set_t *src2)`

  `sched.h` (GNU): Limiting execution to certain CPUs.

`void CPU_ZERO (cpu_set_t *set)`

  `sched.h` (GNU): Limiting execution to certain CPUs.

`tcflag_t CREAD`

  `termios.h` (POSIX.1): Control Modes.

`tcflag_t CRTS_IFLOW`

  `termios.h` (BSD): Control Modes.

`tcflag_t CS5`

  `termios.h` (POSIX.1): Control Modes.

`tcflag_t CS6`

  `termios.h` (POSIX.1): Control Modes.

`tcflag_t CS7`

  `termios.h` (POSIX.1): Control Modes.

`tcflag_t CS8`

  `termios.h` (POSIX.1): Control Modes.

`tcflag_t CSIZE`

  `termios.h` (POSIX.1): Control Modes.

`tcflag_t CSTOPB`

  `termios.h` (POSIX.1): Control Modes.

`DBL_DIG`

  `float.h` (C90): Floating Point Parameters.

`DBL_EPSILON`

  `float.h` (C90): Floating Point Parameters.

`DBL_MANT_DIG`

  `float.h` (C90): Floating Point Parameters.

`DBL_MAX`

  `float.h` (C90): Floating Point Parameters.

`DBL_MAX_10_EXP`

  `float.h` (C90): Floating Point Parameters.

`DBL_MAX_EXP`

  `float.h` (C90): Floating Point Parameters.

`DBL_MIN`

  `float.h` (C90): Floating Point Parameters.

`DBL_MIN_10_EXP`

  `float.h` (C90): Floating Point Parameters.

`DBL_MIN_EXP`

  `float.h` (C90): Floating Point Parameters.

`DEAD_PROCESS`

  `utmp.h` (SVID): Manipulating the User Accounting Database.

  `utmpx.h` (XPG4.2): XPG User Accounting Database Functions.

`DIR`

  `dirent.h` (POSIX.1): Opening a Directory Stream.

`int DLFO_EH_SEGMENT_TYPE`

  `dlfcn.h` (GNU): Dynamic Linker Introspection.

`int DLFO_STRUCT_HAS_EH_COUNT`

  `dlfcn.h` (GNU): Dynamic Linker Introspection.

`int DLFO_STRUCT_HAS_EH_DBASE`

  `dlfcn.h` (GNU): Dynamic Linker Introspection.

`mode_t DTTOIF (int dtype)`

  `dirent.h` (BSD): Format of a Directory Entry.

`int E2BIG`

  `errno.h` (POSIX.1): Error Codes.

`int EACCES`

  `errno.h` (POSIX.1): Error Codes.

`int EADDRINUSE`

  `errno.h` (BSD): Error Codes.

`int EADDRNOTAVAIL`

  `errno.h` (BSD): Error Codes.

`int EADV`

  `errno.h` (Linux???): Error Codes.

`int EAFNOSUPPORT`

  `errno.h` (BSD): Error Codes.

`int EAGAIN`

  `errno.h` (POSIX.1): Error Codes.

`int EALREADY`

  `errno.h` (BSD): Error Codes.

`int EAUTH`

  `errno.h` (BSD): Error Codes.

`int EBACKGROUND`

  `errno.h` (GNU): Error Codes.

`int EBADE`

  `errno.h` (Linux???): Error Codes.

`int EBADF`

  `errno.h` (POSIX.1): Error Codes.

`int EBADFD`

  `errno.h` (Linux???): Error Codes.

`int EBADMSG`

  `errno.h` (XOPEN): Error Codes.

`int EBADR`

  `errno.h` (Linux???): Error Codes.

`int EBADRPC`

  `errno.h` (BSD): Error Codes.

`int EBADRQC`

  `errno.h` (Linux???): Error Codes.

`int EBADSLT`

  `errno.h` (Linux???): Error Codes.

`int EBFONT`

  `errno.h` (Linux???): Error Codes.

`int EBUSY`

  `errno.h` (POSIX.1): Error Codes.

`int ECANCELED`

  `errno.h` (POSIX.1): Error Codes.

`int ECHILD`

  `errno.h` (POSIX.1): Error Codes.

`tcflag_t ECHO`

  `termios.h` (POSIX.1): Local Modes.

`tcflag_t ECHOCTL`

  `termios.h` (BSD): Local Modes.

`tcflag_t ECHOE`

  `termios.h` (POSIX.1): Local Modes.

`tcflag_t ECHOK`

  `termios.h` (POSIX.1): Local Modes.

`tcflag_t ECHOKE`

  `termios.h` (BSD): Local Modes.

`tcflag_t ECHONL`

  `termios.h` (POSIX.1): Local Modes.

`tcflag_t ECHOPRT`

  `termios.h` (BSD): Local Modes.

`int ECHRNG`

  `errno.h` (Linux???): Error Codes.

`int ECOMM`

  `errno.h` (Linux???): Error Codes.

`int ECONNABORTED`

  `errno.h` (BSD): Error Codes.

`int ECONNREFUSED`

  `errno.h` (BSD): Error Codes.

`int ECONNRESET`

  `errno.h` (BSD): Error Codes.

`int ED`

  `errno.h` (GNU): Error Codes.

`int EDEADLK`

  `errno.h` (POSIX.1): Error Codes.

`int EDEADLOCK`

  `errno.h` (Linux???): Error Codes.

`int EDESTADDRREQ`

  `errno.h` (BSD): Error Codes.

`int EDIED`

  `errno.h` (GNU): Error Codes.

`int EDOM`

  `errno.h` (ISO): Error Codes.

`int EDOTDOT`

  `errno.h` (Linux???): Error Codes.

`int EDQUOT`

  `errno.h` (BSD): Error Codes.

`int EEXIST`

  `errno.h` (POSIX.1): Error Codes.

`int EFAULT`

  `errno.h` (POSIX.1): Error Codes.

`int EFBIG`

  `errno.h` (POSIX.1): Error Codes.

`int EFTYPE`

  `errno.h` (BSD): Error Codes.

`int EGRATUITOUS`

  `errno.h` (GNU): Error Codes.

`int EGREGIOUS`

  `errno.h` (GNU): Error Codes.

`int EHOSTDOWN`

  `errno.h` (BSD): Error Codes.

`int EHOSTUNREACH`

  `errno.h` (BSD): Error Codes.

`int EHWPOISON`

  `errno.h` (Linux): Error Codes.

`int EIDRM`

  `errno.h` (XOPEN): Error Codes.

`int EIEIO`

  `errno.h` (GNU): Error Codes.

`int EILSEQ`

  `errno.h` (ISO): Error Codes.

`int EINPROGRESS`

  `errno.h` (BSD): Error Codes.

`int EINTR`

  `errno.h` (POSIX.1): Error Codes.

`int EINVAL`

  `errno.h` (POSIX.1): Error Codes.

`int EIO`

  `errno.h` (POSIX.1): Error Codes.

`int EISCONN`

  `errno.h` (BSD): Error Codes.

`int EISDIR`

  `errno.h` (POSIX.1): Error Codes.

`int EISNAM`

  `errno.h` (Linux???): Error Codes.

`int EKEYEXPIRED`

  `errno.h` (Linux): Error Codes.

`int EKEYREJECTED`

  `errno.h` (Linux): Error Codes.

`int EKEYREVOKED`

  `errno.h` (Linux): Error Codes.

`int EL2HLT`

  `errno.h` (Obsolete): Error Codes.

`int EL2NSYNC`

  `errno.h` (Obsolete): Error Codes.

`int EL3HLT`

  `errno.h` (Obsolete): Error Codes.

`int EL3RST`

  `errno.h` (Obsolete): Error Codes.

`int ELIBACC`

  `errno.h` (Linux???): Error Codes.

`int ELIBBAD`

  `errno.h` (Linux???): Error Codes.

`int ELIBEXEC`

  `errno.h` (GNU): Error Codes.

`int ELIBMAX`

  `errno.h` (Linux???): Error Codes.

`int ELIBSCN`

  `errno.h` (Linux???): Error Codes.

`int ELNRNG`

  `errno.h` (Linux???): Error Codes.

`int ELOOP`

  `errno.h` (BSD): Error Codes.

`int EMEDIUMTYPE`

  `errno.h` (Linux???): Error Codes.

`int EMFILE`

  `errno.h` (POSIX.1): Error Codes.

`int EMLINK`

  `errno.h` (POSIX.1): Error Codes.

`EMPTY`

  `utmp.h` (SVID): Manipulating the User Accounting Database.

  `utmpx.h` (XPG4.2): XPG User Accounting Database Functions.

`int EMSGSIZE`

  `errno.h` (BSD): Error Codes.

`int EMULTIHOP`

  `errno.h` (XOPEN): Error Codes.

`int ENAMETOOLONG`

  `errno.h` (POSIX.1): Error Codes.

`int ENAVAIL`

  `errno.h` (Linux???): Error Codes.

`int ENEEDAUTH`

  `errno.h` (BSD): Error Codes.

`int ENETDOWN`

  `errno.h` (BSD): Error Codes.

`int ENETRESET`

  `errno.h` (BSD): Error Codes.

`int ENETUNREACH`

  `errno.h` (BSD): Error Codes.

`int ENFILE`

  `errno.h` (POSIX.1): Error Codes.

`int ENOANO`

  `errno.h` (Linux???): Error Codes.

`int ENOBUFS`

  `errno.h` (BSD): Error Codes.

`int ENOCSI`

  `errno.h` (Linux???): Error Codes.

`int ENODATA`

  `errno.h` (XOPEN): Error Codes.

`int ENODEV`

  `errno.h` (POSIX.1): Error Codes.

`int ENOENT`

  `errno.h` (POSIX.1): Error Codes.

`int ENOEXEC`

  `errno.h` (POSIX.1): Error Codes.

`int ENOKEY`

  `errno.h` (Linux): Error Codes.

`int ENOLCK`

  `errno.h` (POSIX.1): Error Codes.

`int ENOLINK`

  `errno.h` (XOPEN): Error Codes.

`int ENOMEDIUM`

  `errno.h` (Linux???): Error Codes.

`int ENOMEM`

  `errno.h` (POSIX.1): Error Codes.

`int ENOMSG`

  `errno.h` (XOPEN): Error Codes.

`int ENONET`

  `errno.h` (Linux???): Error Codes.

`int ENOPKG`

  `errno.h` (Linux???): Error Codes.

`int ENOPROTOOPT`

  `errno.h` (BSD): Error Codes.

`int ENOSPC`

  `errno.h` (POSIX.1): Error Codes.

`int ENOSR`

  `errno.h` (XOPEN): Error Codes.

`int ENOSTR`

  `errno.h` (XOPEN): Error Codes.

`int ENOSYS`

  `errno.h` (POSIX.1): Error Codes.

`int ENOTBLK`

  `errno.h` (BSD): Error Codes.

`int ENOTCONN`

  `errno.h` (BSD): Error Codes.

`int ENOTDIR`

  `errno.h` (POSIX.1): Error Codes.

`int ENOTEMPTY`

  `errno.h` (POSIX.1): Error Codes.

`int ENOTNAM`

  `errno.h` (Linux???): Error Codes.

`int ENOTRECOVERABLE`

  `errno.h` (GNU): Error Codes.

`int ENOTSOCK`

  `errno.h` (BSD): Error Codes.

`int ENOTSUP`

  `errno.h` (POSIX.1): Error Codes.

`int ENOTTY`

  `errno.h` (POSIX.1): Error Codes.

`int ENOTUNIQ`

  `errno.h` (Linux???): Error Codes.

`int ENXIO`

  `errno.h` (POSIX.1): Error Codes.

`int EOF`

  `stdio.h` (ISO): End-Of-File and Errors.

`int EOPNOTSUPP`

  `errno.h` (BSD): Error Codes.

`int EOVERFLOW`

  `errno.h` (XOPEN): Error Codes.

`int EOWNERDEAD`

  `errno.h` (GNU): Error Codes.

`int EPERM`

  `errno.h` (POSIX.1): Error Codes.

`int EPFNOSUPPORT`

  `errno.h` (BSD): Error Codes.

`int EPIPE`

  `errno.h` (POSIX.1): Error Codes.

`int EPROCLIM`

  `errno.h` (BSD): Error Codes.

`int EPROCUNAVAIL`

  `errno.h` (BSD): Error Codes.

`int EPROGMISMATCH`

  `errno.h` (BSD): Error Codes.

`int EPROGUNAVAIL`

  `errno.h` (BSD): Error Codes.

`int EPROTO`

  `errno.h` (XOPEN): Error Codes.

`int EPROTONOSUPPORT`

  `errno.h` (BSD): Error Codes.

`int EPROTOTYPE`

  `errno.h` (BSD): Error Codes.

`int EQUIV_CLASS_MAX`

  `limits.h` (POSIX.2): Utility Program Capacity Limits.

`int ERANGE`

  `errno.h` (ISO): Error Codes.

`int EREMCHG`

  `errno.h` (Linux???): Error Codes.

`int EREMOTE`

  `errno.h` (BSD): Error Codes.

`int EREMOTEIO`

  `errno.h` (Linux???): Error Codes.

`int ERESTART`

  `errno.h` (Linux???): Error Codes.

`int ERFKILL`

  `errno.h` (Linux): Error Codes.

`int EROFS`

  `errno.h` (POSIX.1): Error Codes.

`int ERPCMISMATCH`

  `errno.h` (BSD): Error Codes.

`int ESHUTDOWN`

  `errno.h` (BSD): Error Codes.

`int ESOCKTNOSUPPORT`

  `errno.h` (BSD): Error Codes.

`int ESPIPE`

  `errno.h` (POSIX.1): Error Codes.

`int ESRCH`

  `errno.h` (POSIX.1): Error Codes.

`int ESRMNT`

  `errno.h` (Linux???): Error Codes.

`int ESTALE`

  `errno.h` (BSD): Error Codes.

`int ESTRPIPE`

  `errno.h` (Linux???): Error Codes.

`int ETIME`

  `errno.h` (XOPEN): Error Codes.

`int ETIMEDOUT`

  `errno.h` (BSD): Error Codes.

`int ETOOMANYREFS`

  `errno.h` (BSD): Error Codes.

`int ETXTBSY`

  `errno.h` (BSD): Error Codes.

`int EUCLEAN`

  `errno.h` (Linux???): Error Codes.

`int EUNATCH`

  `errno.h` (Linux???): Error Codes.

`int EUSERS`

  `errno.h` (BSD): Error Codes.

`int EWOULDBLOCK`

  `errno.h` (BSD): Error Codes.

`int EXDEV`

  `errno.h` (POSIX.1): Error Codes.

`int EXFULL`

  `errno.h` (Linux???): Error Codes.

`int EXIT_FAILURE`

  `stdlib.h` (ISO): Exit Status.

`int EXIT_SUCCESS`

  `stdlib.h` (ISO): Exit Status.

`int EXPR_NEST_MAX`

  `limits.h` (POSIX.2): Utility Program Capacity Limits.

`int FD_CLOEXEC`

  `fcntl.h` (POSIX.1): File Descriptor Flags.

`void FD_CLR (int filedes, fd_set *set)`

  `sys/select.h` (POSIX.1): Waiting for Input or Output.

`int FD_ISSET (int filedes, const fd_set *set)`

  `sys/select.h` (POSIX.1): Waiting for Input or Output.

`void FD_SET (int filedes, fd_set *set)`

  `sys/select.h` (POSIX.1): Waiting for Input or Output.

`int FD_SETSIZE`

  `sys/select.h` (POSIX.1): Waiting for Input or Output.

`void FD_ZERO (fd_set *set)`

  `sys/select.h` (POSIX.1): Waiting for Input or Output.

`FE_DIVBYZERO`

  `fenv.h` (ISO): Examining the FPU status word.

`FE_DOWNWARD`

  `fenv.h` (ISO): Rounding Modes.

`FE_INEXACT`

  `fenv.h` (ISO): Examining the FPU status word.

`FE_INVALID`

  `fenv.h` (ISO): Examining the FPU status word.

`FE_OVERFLOW`

  `fenv.h` (ISO): Examining the FPU status word.

`int FE_SNANS_ALWAYS_SIGNAL`

  `fenv.h` (ISO): Infinity and NaN.

`FE_TONEAREST`

  `fenv.h` (ISO): Rounding Modes.

`FE_TOWARDZERO`

  `fenv.h` (ISO): Rounding Modes.

`FE_UNDERFLOW`

  `fenv.h` (ISO): Examining the FPU status word.

`FE_UPWARD`

  `fenv.h` (ISO): Rounding Modes.

`FILE`

  `stdio.h` (ISO): Streams.

`int FILENAME_MAX`

  `stdio.h` (ISO): Limits on File System Capacity.

`FLT_DIG`

  `float.h` (C90): Floating Point Parameters.

`FLT_EPSILON`

  `float.h` (C90): Floating Point Parameters.

`FLT_MANT_DIG`

  `float.h` (C90): Floating Point Parameters.

`FLT_MAX`

  `float.h` (C90): Floating Point Parameters.

`FLT_MAX_10_EXP`

  `float.h` (C90): Floating Point Parameters.

`FLT_MAX_EXP`

  `float.h` (C90): Floating Point Parameters.

`FLT_MIN`

  `float.h` (C90): Floating Point Parameters.

`FLT_MIN_10_EXP`

  `float.h` (C90): Floating Point Parameters.

`FLT_MIN_EXP`

  `float.h` (C90): Floating Point Parameters.

`FLT_RADIX`

  `float.h` (C90): Floating Point Parameters.

`FLT_ROUNDS`

  `float.h` (C90): Floating Point Parameters.

`tcflag_t FLUSHO`

  `termios.h` (BSD): Local Modes.

`FNM_CASEFOLD`

  `fnmatch.h` (POSIX.1-2024): Wildcard Matching.

`FNM_EXTMATCH`

  `fnmatch.h` (GNU): Wildcard Matching.

`FNM_FILE_NAME`

  `fnmatch.h` (GNU): Wildcard Matching.

`FNM_LEADING_DIR`

  `fnmatch.h` (GNU): Wildcard Matching.

`FNM_NOESCAPE`

  `fnmatch.h` (POSIX.2): Wildcard Matching.

`FNM_PATHNAME`

  `fnmatch.h` (POSIX.2): Wildcard Matching.

`FNM_PERIOD`

  `fnmatch.h` (POSIX.2): Wildcard Matching.

`int FOPEN_MAX`

  `stdio.h` (ISO): Opening Streams.

`FPE_DECOVF_TRAP`

  `signal.h` (BSD): Program Error Signals.

`FPE_FLTDIV_FAULT`

  `signal.h` (BSD): Program Error Signals.

`FPE_FLTDIV_TRAP`

  `signal.h` (BSD): Program Error Signals.

`FPE_FLTOVF_FAULT`

  `signal.h` (BSD): Program Error Signals.

`FPE_FLTOVF_TRAP`

  `signal.h` (BSD): Program Error Signals.

`FPE_FLTUND_FAULT`

  `signal.h` (BSD): Program Error Signals.

`FPE_FLTUND_TRAP`

  `signal.h` (BSD): Program Error Signals.

`FPE_INTDIV_TRAP`

  `signal.h` (BSD): Program Error Signals.

`FPE_INTOVF_TRAP`

  `signal.h` (BSD): Program Error Signals.

`FPE_SUBRNG_TRAP`

  `signal.h` (BSD): Program Error Signals.

`int FP_ILOGB0`

  `math.h` (ISO): Exponentiation and Logarithms.

`int FP_ILOGBNAN`

  `math.h` (ISO): Exponentiation and Logarithms.

`FP_INFINITE`

  `math.h` (C99): Floating-Point Number Classification Functions.

`FP_INT_DOWNWARD`

  `math.h` (ISO): Rounding Functions.

`FP_INT_TONEAREST`

  `math.h` (ISO): Rounding Functions.

`FP_INT_TONEARESTFROMZERO`

  `math.h` (ISO): Rounding Functions.

`FP_INT_TOWARDZERO`

  `math.h` (ISO): Rounding Functions.

`FP_INT_UPWARD`

  `math.h` (ISO): Rounding Functions.

`long int FP_LLOGB0`

  `math.h` (ISO): Exponentiation and Logarithms.

`long int FP_LLOGBNAN`

  `math.h` (ISO): Exponentiation and Logarithms.

`FP_NAN`

  `math.h` (C99): Floating-Point Number Classification Functions.

`FP_NORMAL`

  `math.h` (C99): Floating-Point Number Classification Functions.

`FP_SUBNORMAL`

  `math.h` (C99): Floating-Point Number Classification Functions.

`FP_ZERO`

  `math.h` (C99): Floating-Point Number Classification Functions.

`struct FTW`

  `ftw.h` (XPG4.2): Working with Directory Trees.

`int F_DUPFD`

  `fcntl.h` (POSIX.1): Duplicating Descriptors.

`int F_GETFD`

  `fcntl.h` (POSIX.1): File Descriptor Flags.

`int F_GETFL`

  `fcntl.h` (POSIX.1): Getting and Setting File Status Flags.

`int F_GETLK`

  `fcntl.h` (POSIX.1): File Locks.

`int F_GETOWN`

  `fcntl.h` (BSD): Interrupt-Driven Input.

`int F_OFD_SETLK`

  `fcntl.h` (POSIX.1): Open File Description Locks.

`int F_OFD_SETLKW`

  `fcntl.h` (POSIX.1): Open File Description Locks.

`int F_OK`

  `unistd.h` (POSIX.1): Testing Permission to Access a File.

`F_RDLCK`

  `fcntl.h` (POSIX.1): File Locks.

`int F_SETFD`

  `fcntl.h` (POSIX.1): File Descriptor Flags.

`int F_SETFL`

  `fcntl.h` (POSIX.1): Getting and Setting File Status Flags.

`int F_SETLK`

  `fcntl.h` (POSIX.1): File Locks.

`int F_SETLKW`

  `fcntl.h` (POSIX.1): File Locks.

`int F_SETOWN`

  `fcntl.h` (BSD): Interrupt-Driven Input.

`F_UNLCK`

  `fcntl.h` (POSIX.1): File Locks.

`F_WRLCK`

  `fcntl.h` (POSIX.1): File Locks.

`GLOB_ABORTED`

  `glob.h` (POSIX.2): Calling `glob`.

`GLOB_ALTDIRFUNC`

  `glob.h` (GNU): More Flags for Globbing.

`GLOB_APPEND`

  `glob.h` (POSIX.2): Flags for Globbing.

`GLOB_BRACE`

  `glob.h` (GNU): More Flags for Globbing.

`GLOB_DOOFFS`

  `glob.h` (POSIX.2): Flags for Globbing.

`GLOB_ERR`

  `glob.h` (POSIX.2): Flags for Globbing.

`GLOB_MAGCHAR`

  `glob.h` (GNU): More Flags for Globbing.

`GLOB_MARK`

  `glob.h` (POSIX.2): Flags for Globbing.

`GLOB_NOCHECK`

  `glob.h` (POSIX.2): Flags for Globbing.

`GLOB_NOESCAPE`

  `glob.h` (POSIX.2): Flags for Globbing.

`GLOB_NOMAGIC`

  `glob.h` (GNU): More Flags for Globbing.

`GLOB_NOMATCH`

  `glob.h` (POSIX.2): Calling `glob`.

`GLOB_NOSORT`

  `glob.h` (POSIX.2): Flags for Globbing.

`GLOB_NOSPACE`

  `glob.h` (POSIX.2): Calling `glob`.

`GLOB_ONLYDIR`

  `glob.h` (GNU): More Flags for Globbing.

`GLOB_PERIOD`

  `glob.h` (GNU): More Flags for Globbing.

`GLOB_TILDE`

  `glob.h` (GNU): More Flags for Globbing.

`GLOB_TILDE_CHECK`

  `glob.h` (GNU): More Flags for Globbing.

`HOST_NOT_FOUND`

  `netdb.h` (BSD): Host Names.

`double HUGE_VAL`

  `math.h` (ISO): Error Reporting by Mathematical Functions.

`float HUGE_VALF`

  `math.h` (ISO): Error Reporting by Mathematical Functions.

`long double HUGE_VALL`

  `math.h` (ISO): Error Reporting by Mathematical Functions.

`_FloatN HUGE_VAL_FN`

  `math.h` (TS 18661-3:2015): Error Reporting by Mathematical Functions.

`_FloatNx HUGE_VAL_FNx`

  `math.h` (TS 18661-3:2015): Error Reporting by Mathematical Functions.

`tcflag_t HUPCL`

  `termios.h` (POSIX.1): Control Modes.

`const float complex I`

  `complex.h` (C99): Complex Numbers.

`tcflag_t ICANON`

  `termios.h` (POSIX.1): Local Modes.

`tcflag_t ICRNL`

  `termios.h` (POSIX.1): Input Modes.

`tcflag_t IEXTEN`

  `termios.h` (POSIX.1): Local Modes.

`size_t IFNAMSIZ`

  `net/if.h` (???): Interface Naming.

`int IFTODT (mode_t mode)`

  `dirent.h` (BSD): Format of a Directory Entry.

`tcflag_t IGNBRK`

  `termios.h` (POSIX.1): Input Modes.

`tcflag_t IGNCR`

  `termios.h` (POSIX.1): Input Modes.

`tcflag_t IGNPAR`

  `termios.h` (POSIX.1): Input Modes.

`tcflag_t IMAXBEL`

  `termios.h` (BSD): Input Modes.

`uint32_t INADDR_ANY`

  `netinet/in.h` (BSD): Host Address Data Type.

`uint32_t INADDR_BROADCAST`

  `netinet/in.h` (BSD): Host Address Data Type.

`uint32_t INADDR_LOOPBACK`

  `netinet/in.h` (BSD): Host Address Data Type.

`uint32_t INADDR_NONE`

  `netinet/in.h` (BSD): Host Address Data Type.

`float INFINITY`

  `math.h` (ISO): Infinity and NaN.

`INIT_PROCESS`

  `utmp.h` (SVID): Manipulating the User Accounting Database.

  `utmpx.h` (XPG4.2): XPG User Accounting Database Functions.

`tcflag_t INLCR`

  `termios.h` (POSIX.1): Input Modes.

`tcflag_t INPCK`

  `termios.h` (POSIX.1): Input Modes.

`INTPTR_WIDTH`

  `stdint.h` (ISO): Width of an Integer Type.

`INT_MAX`

  `limits.h` (ISO): Range of an Integer Type.

`INT_MIN`

  `limits.h` (ISO): Range of an Integer Type.

`INT_WIDTH`

  `limits.h` (ISO): Width of an Integer Type.

`int IPPORT_RESERVED`

  `netinet/in.h` (BSD): Internet Ports.

`int IPPORT_USERRESERVED`

  `netinet/in.h` (BSD): Internet Ports.

`tcflag_t ISIG`

  `termios.h` (POSIX.1): Local Modes.

`tcflag_t ISTRIP`

  `termios.h` (POSIX.1): Input Modes.

`ITIMER_PROF`

  `sys/time.h` (BSD): Setting an Alarm.

`ITIMER_REAL`

  `sys/time.h` (BSD): Setting an Alarm.

`ITIMER_VIRTUAL`

  `sys/time.h` (BSD): Setting an Alarm.

`tcflag_t IXANY`

  `termios.h` (BSD): Input Modes.

`tcflag_t IXOFF`

  `termios.h` (POSIX.1): Input Modes.

`tcflag_t IXON`

  `termios.h` (POSIX.1): Input Modes.

`LANG`

  `locale.h` (ISO): Locale Categories.

`LC_ALL`

  `locale.h` (ISO): Locale Categories.

`LC_COLLATE`

  `locale.h` (ISO): Locale Categories.

`LC_CTYPE`

  `locale.h` (ISO): Locale Categories.

`LC_MESSAGES`

  `locale.h` (XOPEN): Locale Categories.

`LC_MONETARY`

  `locale.h` (ISO): Locale Categories.

`LC_NUMERIC`

  `locale.h` (ISO): Locale Categories.

`LC_TIME`

  `locale.h` (ISO): Locale Categories.

`LDBL_DIG`

  `float.h` (C90): Floating Point Parameters.

`LDBL_EPSILON`

  `float.h` (C90): Floating Point Parameters.

`LDBL_MANT_DIG`

  `float.h` (C90): Floating Point Parameters.

`LDBL_MAX`

  `float.h` (C90): Floating Point Parameters.

`LDBL_MAX_10_EXP`

  `float.h` (C90): Floating Point Parameters.

`LDBL_MAX_EXP`

  `float.h` (C90): Floating Point Parameters.

`LDBL_MIN`

  `float.h` (C90): Floating Point Parameters.

`LDBL_MIN_10_EXP`

  `float.h` (C90): Floating Point Parameters.

`LDBL_MIN_EXP`

  `float.h` (C90): Floating Point Parameters.

`int LINE_MAX`

  `limits.h` (POSIX.2): Utility Program Capacity Limits.

`int LINK_MAX`

  `limits.h` optional (POSIX.1): Limits on File System Capacity.

`LLONG_MAX`

  `limits.h` (ISO): Range of an Integer Type.

`LLONG_MIN`

  `limits.h` (ISO): Range of an Integer Type.

`LLONG_WIDTH`

  `limits.h` (ISO): Width of an Integer Type.

`LOGIN_PROCESS`

  `utmp.h` (SVID): Manipulating the User Accounting Database.

  `utmpx.h` (XPG4.2): XPG User Accounting Database Functions.

`LONG_LONG_MAX`

  `limits.h` (GNU): Range of an Integer Type.

`LONG_LONG_MIN`

  `limits.h` (GNU): Range of an Integer Type.

`LONG_MAX`

  `limits.h` (ISO): Range of an Integer Type.

`LONG_MIN`

  `limits.h` (ISO): Range of an Integer Type.

`LONG_WIDTH`

  `limits.h` (ISO): Width of an Integer Type.

`L_INCR`

  `sys/file.h` (BSD): File Positioning.

`L_SET`

  `sys/file.h` (BSD): File Positioning.

`L_XTND`

  `sys/file.h` (BSD): File Positioning.

`int L_ctermid`

  `stdio.h` (POSIX.1): Identifying the Controlling Terminal.

`int L_cuserid`

  `stdio.h` (POSIX.1): Identifying Who Logged In.

`int L_tmpnam`

  `stdio.h` (ISO): Temporary Files.

`MADV_HUGEPAGE`

  `sys/mman.h` (Linux): Memory-mapped I/O.

`MAP_ANON`

  `sys/mman.h` (POSIX.1-2024): Memory-mapped I/O.

`MAP_ANONYMOUS`

  `sys/mman.h` (POSIX.1-2024): Memory-mapped I/O.

`MAP_HUGETLB`

  `sys/mman.h` (Linux): Memory-mapped I/O.

`int MAXNAMLEN`

  `dirent.h` (BSD): Limits on File System Capacity.

`int MAXSYMLINKS`

  `sys/param.h` (BSD): Symbolic Links.

`int MAX_CANON`

  `limits.h` (POSIX.1): Limits on File System Capacity.

`int MAX_INPUT`

  `limits.h` (POSIX.1): Limits on File System Capacity.

`int MB_CUR_MAX`

  `stdlib.h` (ISO): Selecting the conversion and its properties.

`int MB_LEN_MAX`

  `limits.h` (ISO): Selecting the conversion and its properties.

`tcflag_t MDMBUF`

  `termios.h` (BSD): Control Modes.

`MFD_ALLOW_SEALING`

  `sys/mman.h` (Linux): Memory-mapped I/O.

`MFD_CLOEXEC`

  `sys/mman.h` (Linux): Memory-mapped I/O.

`MFD_HUGETLB`

  `sys/mman.h` (Linux): Memory-mapped I/O.

`MLOCK_ONFAULT`

  `sys/mman.h` (Linux): Functions To Lock And Unlock Pages.

`int MSG_DONTROUTE`

  `sys/socket.h` (BSD): Socket Data Options.

`int MSG_OOB`

  `sys/socket.h` (BSD): Socket Data Options.

`int MSG_PEEK`

  `sys/socket.h` (BSD): Socket Data Options.

`int NAME_MAX`

  `limits.h` (POSIX.1): Limits on File System Capacity.

`float NAN`

  `math.h` (GNU): Infinity and NaN.

`int NCCS`

  `termios.h` (POSIX.1): Terminal Mode Data Types.

`NEW_TIME`

  `utmp.h` (SVID): Manipulating the User Accounting Database.

  `utmpx.h` (XPG4.2): XPG User Accounting Database Functions.

`int NGROUPS_MAX`

  `limits.h` (POSIX.1): General Capacity Limits.

`tcflag_t NOFLSH`

  `termios.h` (POSIX.1): Local Modes.

`tcflag_t NOKERNINFO`

  `termios.h` optional (BSD): Local Modes.

`NO_ADDRESS`

  `netdb.h` (BSD): Host Names.

`NO_RECOVERY`

  `netdb.h` (BSD): Host Names.

`int NSIG`

  `signal.h` (BSD): Standard Signals.

`void * NULL`

  `stddef.h` (ISO): Null Pointer Constant.

`OLD_TIME`

  `utmp.h` (SVID): Manipulating the User Accounting Database.

  `utmpx.h` (XPG4.2): XPG User Accounting Database Functions.

`ONCE_FLAG_INIT`

  `threads.h` (C11): Call Once.

`tcflag_t ONLCR`

  `termios.h` (POSIX.1): Output Modes.

`tcflag_t ONOEOT`

  `termios.h` optional (BSD): Output Modes.

`int OPEN_MAX`

  `limits.h` (POSIX.1): General Capacity Limits.

`tcflag_t OPOST`

  `termios.h` (POSIX.1): Output Modes.

`OPTION_ALIAS`

  `argp.h` (GNU): Flags for Argp Options.

`OPTION_ARG_OPTIONAL`

  `argp.h` (GNU): Flags for Argp Options.

`OPTION_DOC`

  `argp.h` (GNU): Flags for Argp Options.

`OPTION_HIDDEN`

  `argp.h` (GNU): Flags for Argp Options.

`OPTION_NO_USAGE`

  `argp.h` (GNU): Flags for Argp Options.

`tcflag_t OXTABS`

  `termios.h` optional (BSD): Output Modes.

`int O_ACCMODE`

  `fcntl.h` (POSIX.1): File Access Modes.

`int O_APPEND`

  `fcntl.h` (POSIX.1): I/O Operating Modes.

`int O_ASYNC`

  `fcntl.h` (BSD): I/O Operating Modes.

`int O_CREAT`

  `fcntl.h` (POSIX.1): Open-time Flags.

`int O_DIRECTORY`

  `fcntl.h` (POSIX.1): Open-time Flags.

`int O_EXCL`

  `fcntl.h` (POSIX.1): Open-time Flags.

`int O_EXEC`

  `fcntl.h` optional (GNU): File Access Modes.

`int O_EXLOCK`

  `fcntl.h` optional (BSD): Open-time Flags.

`int O_FSYNC`

  `fcntl.h` (BSD): I/O Operating Modes.

`int O_IGNORE_CTTY`

  `fcntl.h` optional (GNU): Open-time Flags.

`int O_NDELAY`

  `fcntl.h` (BSD): I/O Operating Modes.

`int O_NOATIME`

  `fcntl.h` (GNU): I/O Operating Modes.

`int O_NOCTTY`

  `fcntl.h` (POSIX.1): Open-time Flags.

`int O_NOFOLLOW`

  `fcntl.h` (POSIX.1): Open-time Flags.

`int O_NOLINK`

  `fcntl.h` optional (GNU): Open-time Flags.

`int O_NONBLOCK`

  `fcntl.h` (POSIX.1): Open-time Flags.

  `fcntl.h` (POSIX.1): I/O Operating Modes.

`int O_NOTRANS`

  `fcntl.h` optional (GNU): Open-time Flags.

`int O_PATH`

  `fcntl.h` (Linux): File Access Modes.

`int O_RDONLY`

  `fcntl.h` (POSIX.1): File Access Modes.

`int O_RDWR`

  `fcntl.h` (POSIX.1): File Access Modes.

`int O_READ`

  `fcntl.h` optional (GNU): File Access Modes.

`int O_SHLOCK`

  `fcntl.h` optional (BSD): Open-time Flags.

`int O_SYNC`

  `fcntl.h` (BSD): I/O Operating Modes.

`int O_TMPFILE`

  `fcntl.h` (GNU): Open-time Flags.

`int O_TRUNC`

  `fcntl.h` (POSIX.1): Open-time Flags.

`int O_WRITE`

  `fcntl.h` optional (GNU): File Access Modes.

`int O_WRONLY`

  `fcntl.h` (POSIX.1): File Access Modes.

`tcflag_t PARENB`

  `termios.h` (POSIX.1): Control Modes.

`tcflag_t PARMRK`

  `termios.h` (POSIX.1): Input Modes.

`tcflag_t PARODD`

  `termios.h` (POSIX.1): Control Modes.

`int PATH_MAX`

  `limits.h` (POSIX.1): Limits on File System Capacity.

`PA_CHAR`

  `printf.h` (GNU): Parsing a Template String.

`PA_DOUBLE`

  `printf.h` (GNU): Parsing a Template String.

`PA_FLAG_LONG`

  `printf.h` (GNU): Parsing a Template String.

`PA_FLAG_LONG_DOUBLE`

  `printf.h` (GNU): Parsing a Template String.

`PA_FLAG_LONG_LONG`

  `printf.h` (GNU): Parsing a Template String.

`int PA_FLAG_MASK`

  `printf.h` (GNU): Parsing a Template String.

`PA_FLAG_PTR`

  `printf.h` (GNU): Parsing a Template String.

`PA_FLAG_SHORT`

  `printf.h` (GNU): Parsing a Template String.

`PA_FLOAT`

  `printf.h` (GNU): Parsing a Template String.

`PA_INT`

  `printf.h` (GNU): Parsing a Template String.

`PA_LAST`

  `printf.h` (GNU): Parsing a Template String.

`PA_POINTER`

  `printf.h` (GNU): Parsing a Template String.

`PA_STRING`

  `printf.h` (GNU): Parsing a Template String.

`tcflag_t PENDIN`

  `termios.h` (BSD): Local Modes.

`int PF_FILE`

  `sys/socket.h` (GNU): Details of Local Namespace.

`int PF_INET`

  `sys/socket.h` (BSD): The Internet Namespace.

`int PF_INET6`

  `sys/socket.h` (X/Open): The Internet Namespace.

`int PF_LOCAL`

  `sys/socket.h` (POSIX): Details of Local Namespace.

`int PF_UNIX`

  `sys/socket.h` (BSD): Details of Local Namespace.

`int PIPE_BUF`

  `limits.h` (POSIX.1): Limits on File System Capacity.

`PKEY_DISABLE_ACCESS`

  `sys/mman.h` (Linux): Memory Protection.

`PKEY_DISABLE_EXECUTE`

  `sys/mman.h` (Linux): Memory Protection.

`PKEY_DISABLE_READ`

  `sys/mman.h` (Linux): Memory Protection.

`PKEY_DISABLE_WRITE`

  `sys/mman.h` (Linux): Memory Protection.

`POSIX_REC_INCR_XFER_SIZE`

  `limits.h` (POSIX.1): Minimum Values for File System Limits.

`POSIX_REC_MAX_XFER_SIZE`

  `limits.h` (POSIX.1): Minimum Values for File System Limits.

`POSIX_REC_MIN_XFER_SIZE`

  `limits.h` (POSIX.1): Minimum Values for File System Limits.

`POSIX_REC_XFER_ALIGN`

  `limits.h` (POSIX.1): Minimum Values for File System Limits.

`PRIO_MAX`

  `sys/resource.h` (BSD): Functions For Traditional Scheduling.

`PRIO_MIN`

  `sys/resource.h` (BSD): Functions For Traditional Scheduling.

`PRIO_PGRP`

  `sys/resource.h` (BSD): Functions For Traditional Scheduling.

`PRIO_PROCESS`

  `sys/resource.h` (BSD): Functions For Traditional Scheduling.

`PRIO_USER`

  `sys/resource.h` (BSD): Functions For Traditional Scheduling.

`PROT_EXEC`

  `sys/mman.h` (POSIX): Memory Protection.

`PROT_NONE`

  `sys/mman.h` (POSIX): Memory Protection.

`PROT_READ`

  `sys/mman.h` (POSIX): Memory Protection.

`PROT_WRITE`

  `sys/mman.h` (POSIX): Memory Protection.

`PTRDIFF_WIDTH`

  `stdint.h` (ISO): Width of an Integer Type.

`char * P_tmpdir`

  `stdio.h` (SVID): Temporary Files.

`int RAND_MAX`

  `stdlib.h` (ISO): ISO C Random Number Functions.

`REG_BADBR`

  `regex.h` (POSIX.2): POSIX Regular Expression Compilation.

`REG_BADPAT`

  `regex.h` (POSIX.2): POSIX Regular Expression Compilation.

`REG_BADRPT`

  `regex.h` (POSIX.2): POSIX Regular Expression Compilation.

`REG_EBRACE`

  `regex.h` (POSIX.2): POSIX Regular Expression Compilation.

`REG_EBRACK`

  `regex.h` (POSIX.2): POSIX Regular Expression Compilation.

`REG_ECOLLATE`

  `regex.h` (POSIX.2): POSIX Regular Expression Compilation.

`REG_ECTYPE`

  `regex.h` (POSIX.2): POSIX Regular Expression Compilation.

`REG_EESCAPE`

  `regex.h` (POSIX.2): POSIX Regular Expression Compilation.

`REG_EPAREN`

  `regex.h` (POSIX.2): POSIX Regular Expression Compilation.

`REG_ERANGE`

  `regex.h` (POSIX.2): POSIX Regular Expression Compilation.

`REG_ESPACE`

  `regex.h` (POSIX.2): POSIX Regular Expression Compilation.

  `regex.h` (POSIX.2): Matching a Compiled POSIX Regular Expression.

`REG_ESUBREG`

  `regex.h` (POSIX.2): POSIX Regular Expression Compilation.

`REG_EXTENDED`

  `regex.h` (POSIX.2): Flags for POSIX Regular Expressions.

`REG_ICASE`

  `regex.h` (POSIX.2): Flags for POSIX Regular Expressions.

`REG_NEWLINE`

  `regex.h` (POSIX.2): Flags for POSIX Regular Expressions.

`REG_NOMATCH`

  `regex.h` (POSIX.2): Matching a Compiled POSIX Regular Expression.

`REG_NOSUB`

  `regex.h` (POSIX.2): Flags for POSIX Regular Expressions.

`REG_NOTBOL`

  `regex.h` (POSIX.2): Matching a Compiled POSIX Regular Expression.

`REG_NOTEOL`

  `regex.h` (POSIX.2): Matching a Compiled POSIX Regular Expression.

`int RE_DUP_MAX`

  `limits.h` (POSIX.2): General Capacity Limits.

`RLIMIT_AS`

  `sys/resource.h` (Unix98): Limiting Resource Usage.

`RLIMIT_CORE`

  `sys/resource.h` (BSD): Limiting Resource Usage.

`RLIMIT_CPU`

  `sys/resource.h` (BSD): Limiting Resource Usage.

`RLIMIT_DATA`

  `sys/resource.h` (BSD): Limiting Resource Usage.

`RLIMIT_FSIZE`

  `sys/resource.h` (BSD): Limiting Resource Usage.

`RLIMIT_MEMLOCK`

  `sys/resource.h` (BSD): Limiting Resource Usage.

`RLIMIT_NOFILE`

  `sys/resource.h` (BSD): Limiting Resource Usage.

`RLIMIT_NPROC`

  `sys/resource.h` (BSD): Limiting Resource Usage.

`RLIMIT_RSS`

  `sys/resource.h` (BSD): Limiting Resource Usage.

`RLIMIT_STACK`

  `sys/resource.h` (BSD): Limiting Resource Usage.

`rlim_t RLIM_INFINITY`

  `sys/resource.h` (BSD): Limiting Resource Usage.

`RLIM_NLIMITS`

  `sys/resource.h` (BSD): Limiting Resource Usage.

`int RSEQ_SIG`

  `sys/rseq.h` (Linux): Restartable Sequences.

`RUN_LVL`

  `utmp.h` (SVID): Manipulating the User Accounting Database.

  `utmpx.h` (XPG4.2): XPG User Accounting Database Functions.

`RUSAGE_CHILDREN`

  `sys/resource.h` (BSD): Resource Usage.

`RUSAGE_SELF`

  `sys/resource.h` (BSD): Resource Usage.

`int R_OK`

  `unistd.h` (POSIX.1): Testing Permission to Access a File.

`int SA_NOCLDSTOP`

  `signal.h` (POSIX.1): Flags for `sigaction`.

`int SA_ONSTACK`

  `signal.h` (BSD): Flags for `sigaction`.

`int SA_RESTART`

  `signal.h` (BSD): Flags for `sigaction`.

`SCHAR_MAX`

  `limits.h` (ISO): Range of an Integer Type.

`SCHAR_MIN`

  `limits.h` (ISO): Range of an Integer Type.

`SCHAR_WIDTH`

  `limits.h` (ISO): Width of an Integer Type.

`int SEEK_CUR`

  `stdio.h` (ISO): File Positioning.

`int SEEK_END`

  `stdio.h` (ISO): File Positioning.

`int SEEK_SET`

  `stdio.h` (ISO): File Positioning.

`SHRT_MAX`

  `limits.h` (ISO): Range of an Integer Type.

`SHRT_MIN`

  `limits.h` (ISO): Range of an Integer Type.

`SHRT_WIDTH`

  `limits.h` (ISO): Width of an Integer Type.

`int SIGABRT`

  `signal.h` (ISO): Program Error Signals.

`int SIGALRM`

  `signal.h` (POSIX.1): Alarm Signals.

`int SIGBUS`

  `signal.h` (BSD): Program Error Signals.

`int SIGCHLD`

  `signal.h` (POSIX.1): Job Control Signals.

`int SIGCLD`

  `signal.h` (SVID): Job Control Signals.

`int SIGCONT`

  `signal.h` (POSIX.1): Job Control Signals.

`int SIGEMT`

  `signal.h` (BSD): Program Error Signals.

`int SIGFPE`

  `signal.h` (ISO): Program Error Signals.

`int SIGHUP`

  `signal.h` (POSIX.1): Termination Signals.

`int SIGILL`

  `signal.h` (ISO): Program Error Signals.

`int SIGINFO`

  `signal.h` (BSD): Miscellaneous Signals.

`int SIGINT`

  `signal.h` (ISO): Termination Signals.

`int SIGIO`

  `signal.h` (BSD): Asynchronous I/O Signals.

`int SIGIOT`

  `signal.h` (Unix): Program Error Signals.

`int SIGKILL`

  `signal.h` (POSIX.1): Termination Signals.

`int SIGLOST`

  `signal.h` (GNU): Operation Error Signals.

`int SIGPIPE`

  `signal.h` (POSIX.1): Operation Error Signals.

`int SIGPOLL`

  `signal.h` (SVID): Asynchronous I/O Signals.

`int SIGPROF`

  `signal.h` (BSD): Alarm Signals.

`int SIGQUIT`

  `signal.h` (POSIX.1): Termination Signals.

`int SIGSEGV`

  `signal.h` (ISO): Program Error Signals.

`int SIGSTOP`

  `signal.h` (POSIX.1): Job Control Signals.

`int SIGSYS`

  `signal.h` (Unix): Program Error Signals.

`int SIGTERM`

  `signal.h` (ISO): Termination Signals.

`int SIGTRAP`

  `signal.h` (BSD): Program Error Signals.

`int SIGTSTP`

  `signal.h` (POSIX.1): Job Control Signals.

`int SIGTTIN`

  `signal.h` (POSIX.1): Job Control Signals.

`int SIGTTOU`

  `signal.h` (POSIX.1): Job Control Signals.

`int SIGURG`

  `signal.h` (BSD): Asynchronous I/O Signals.

`int SIGUSR1`

  `signal.h` (POSIX.1): Miscellaneous Signals.

`int SIGUSR2`

  `signal.h` (POSIX.1): Miscellaneous Signals.

`int SIGVTALRM`

  `signal.h` (BSD): Alarm Signals.

`int SIGWINCH`

  `signal.h` (POSIX.1-2024): Miscellaneous Signals.

`int SIGXCPU`

  `signal.h` (BSD): Operation Error Signals.

`int SIGXFSZ`

  `signal.h` (BSD): Operation Error Signals.

`SIG_ATOMIC_WIDTH`

  `stdint.h` (ISO): Width of an Integer Type.

`SIG_BLOCK`

  `signal.h` (POSIX.1): Process Signal Mask.

`sighandler_t SIG_ERR`

  `signal.h` (ISO): Basic Signal Handling.

`SIG_SETMASK`

  `signal.h` (POSIX.1): Process Signal Mask.

`SIG_UNBLOCK`

  `signal.h` (POSIX.1): Process Signal Mask.

`SIZE_WIDTH`

  `stdint.h` (ISO): Width of an Integer Type.

`double SNAN`

  `math.h` (TS 18661-1:2014): Infinity and NaN.

`float SNANF`

  `math.h` (TS 18661-1:2014): Infinity and NaN.

`_FloatN SNANFN`

  `math.h` (TS 18661-3:2015): Infinity and NaN.

`_FloatNx SNANFNx`

  `math.h` (TS 18661-3:2015): Infinity and NaN.

`long double SNANL`

  `math.h` (TS 18661-1:2014): Infinity and NaN.

`int SOCK_DGRAM`

  `sys/socket.h` (BSD): Communication Styles.

`int SOCK_RAW`

  `sys/socket.h` (BSD): Communication Styles.

`int SOCK_STREAM`

  `sys/socket.h` (BSD): Communication Styles.

`int SOL_SOCKET`

  `sys/socket.h` (BSD): Socket-Level Options.

`SO_BROADCAST`

  `sys/socket.h` (BSD): Socket-Level Options.

`SO_DEBUG`

  `sys/socket.h` (BSD): Socket-Level Options.

`SO_DONTROUTE`

  `sys/socket.h` (BSD): Socket-Level Options.

`SO_ERROR`

  `sys/socket.h` (BSD): Socket-Level Options.

`SO_KEEPALIVE`

  `sys/socket.h` (BSD): Socket-Level Options.

`SO_LINGER`

  `sys/socket.h` (BSD): Socket-Level Options.

`SO_OOBINLINE`

  `sys/socket.h` (BSD): Socket-Level Options.

`SO_RCVBUF`

  `sys/socket.h` (BSD): Socket-Level Options.

`SO_REUSEADDR`

  `sys/socket.h` (BSD): Socket-Level Options.

`SO_SNDBUF`

  `sys/socket.h` (BSD): Socket-Level Options.

`SO_STYLE`

  `sys/socket.h` (GNU): Socket-Level Options.

`SO_TYPE`

  `sys/socket.h` (BSD): Socket-Level Options.

`speed_t SPEED_MAX`

  `termios.h` (GNU): Line Speed.

`ssize_t SSIZE_MAX`

  `limits.h` (POSIX.1): General Capacity Limits.

`STDERR_FILENO`

  `unistd.h` (POSIX.1): Descriptors and Streams.

`STDIN_FILENO`

  `unistd.h` (POSIX.1): Descriptors and Streams.

`STDOUT_FILENO`

  `unistd.h` (POSIX.1): Descriptors and Streams.

`int STREAM_MAX`

  `limits.h` (POSIX.1): General Capacity Limits.

`int SUN_LEN (struct sockaddr_un * ptr)`

  `sys/un.h` (BSD): Details of Local Namespace.

`SYMLINK_MAX`

  `limits.h` (POSIX.1): Minimum Values for File System Limits.

`S_IEXEC`

  `sys/stat.h` (BSD): The Mode Bits for Access Permission.

`S_IFBLK`

  `sys/stat.h` (BSD): Testing the Type of a File.

`S_IFCHR`

  `sys/stat.h` (BSD): Testing the Type of a File.

`S_IFDIR`

  `sys/stat.h` (BSD): Testing the Type of a File.

`S_IFIFO`

  `sys/stat.h` (BSD): Testing the Type of a File.

`S_IFLNK`

  `sys/stat.h` (BSD): Testing the Type of a File.

`int S_IFMT`

  `sys/stat.h` (BSD): Testing the Type of a File.

`S_IFREG`

  `sys/stat.h` (BSD): Testing the Type of a File.

`S_IFSOCK`

  `sys/stat.h` (BSD): Testing the Type of a File.

`S_IREAD`

  `sys/stat.h` (BSD): The Mode Bits for Access Permission.

`S_IRGRP`

  `sys/stat.h` (POSIX.1): The Mode Bits for Access Permission.

`S_IROTH`

  `sys/stat.h` (POSIX.1): The Mode Bits for Access Permission.

`S_IRUSR`

  `sys/stat.h` (POSIX.1): The Mode Bits for Access Permission.

`S_IRWXG`

  `sys/stat.h` (POSIX.1): The Mode Bits for Access Permission.

`S_IRWXO`

  `sys/stat.h` (POSIX.1): The Mode Bits for Access Permission.

`S_IRWXU`

  `sys/stat.h` (POSIX.1): The Mode Bits for Access Permission.

`int S_ISBLK (mode_t m)`

  `sys/stat.h` (POSIX): Testing the Type of a File.

`int S_ISCHR (mode_t m)`

  `sys/stat.h` (POSIX): Testing the Type of a File.

`int S_ISDIR (mode_t m)`

  `sys/stat.h` (POSIX): Testing the Type of a File.

`int S_ISFIFO (mode_t m)`

  `sys/stat.h` (POSIX): Testing the Type of a File.

`S_ISGID`

  `sys/stat.h` (POSIX): The Mode Bits for Access Permission.

`int S_ISLNK (mode_t m)`

  `sys/stat.h` (GNU): Testing the Type of a File.

`int S_ISREG (mode_t m)`

  `sys/stat.h` (POSIX): Testing the Type of a File.

`int S_ISSOCK (mode_t m)`

  `sys/stat.h` (GNU): Testing the Type of a File.

`S_ISUID`

  `sys/stat.h` (POSIX): The Mode Bits for Access Permission.

`S_ISVTX`

  `sys/stat.h` (BSD): The Mode Bits for Access Permission.

`S_IWGRP`

  `sys/stat.h` (POSIX.1): The Mode Bits for Access Permission.

`S_IWOTH`

  `sys/stat.h` (POSIX.1): The Mode Bits for Access Permission.

`S_IWRITE`

  `sys/stat.h` (BSD): The Mode Bits for Access Permission.

`S_IWUSR`

  `sys/stat.h` (POSIX.1): The Mode Bits for Access Permission.

`S_IXGRP`

  `sys/stat.h` (POSIX.1): The Mode Bits for Access Permission.

`S_IXOTH`

  `sys/stat.h` (POSIX.1): The Mode Bits for Access Permission.

`S_IXUSR`

  `sys/stat.h` (POSIX.1): The Mode Bits for Access Permission.

`int S_TYPEISMQ (struct stat *s)`

  `sys/stat.h` (POSIX): Testing the Type of a File.

`int S_TYPEISSEM (struct stat *s)`

  `sys/stat.h` (POSIX): Testing the Type of a File.

`int S_TYPEISSHM (struct stat *s)`

  `sys/stat.h` (POSIX): Testing the Type of a File.

`TCSADRAIN`

  `termios.h` (POSIX.1): Terminal Mode Functions.

`TCSAFLUSH`

  `termios.h` (POSIX.1): Terminal Mode Functions.

`TCSANOW`

  `termios.h` (POSIX.1): Terminal Mode Functions.

`TCSASOFT`

  `termios.h` (BSD): Terminal Mode Functions.

`TEMP_FAILURE_RETRY (expression)`

  `unistd.h` (GNU): Primitives Interrupted by Signals.

`int TIME_UTC`

  `time.h` (ISO): Getting the Time.

`int TMP_MAX`

  `stdio.h` (ISO): Temporary Files.

`tcflag_t TOSTOP`

  `termios.h` (POSIX.1): Local Modes.

`TRY_AGAIN`

  `netdb.h` (BSD): Host Names.

`TSS_DTOR_ITERATIONS`

  `threads.h` (C11): Thread-local Storage.

`int TZNAME_MAX`

  `limits.h` (POSIX.1): General Capacity Limits.

`UCHAR_MAX`

  `limits.h` (ISO): Range of an Integer Type.

`UCHAR_WIDTH`

  `limits.h` (ISO): Width of an Integer Type.

`UINTPTR_WIDTH`

  `stdint.h` (ISO): Width of an Integer Type.

`UINT_MAX`

  `limits.h` (ISO): Range of an Integer Type.

`UINT_WIDTH`

  `limits.h` (ISO): Width of an Integer Type.

`ULLONG_MAX`

  `limits.h` (ISO): Range of an Integer Type.

`ULLONG_WIDTH`

  `limits.h` (ISO): Width of an Integer Type.

`ULONG_LONG_MAX`

  `limits.h` (GNU): Range of an Integer Type.

`ULONG_MAX`

  `limits.h` (ISO): Range of an Integer Type.

`ULONG_WIDTH`

  `limits.h` (ISO): Width of an Integer Type.

`USER_PROCESS`

  `utmp.h` (SVID): Manipulating the User Accounting Database.

  `utmpx.h` (XPG4.2): XPG User Accounting Database Functions.

`USHRT_MAX`

  `limits.h` (ISO): Range of an Integer Type.

`USHRT_WIDTH`

  `limits.h` (ISO): Width of an Integer Type.

`int VDISCARD`

  `termios.h` (BSD): Other Special Characters.

`int VDSUSP`

  `termios.h` (BSD): Characters that Cause Signals.

`int VEOF`

  `termios.h` (POSIX.1): Characters for Input Editing.

`int VEOL`

  `termios.h` (POSIX.1): Characters for Input Editing.

`int VEOL2`

  `termios.h` (BSD): Characters for Input Editing.

`int VERASE`

  `termios.h` (POSIX.1): Characters for Input Editing.

`int VINTR`

  `termios.h` (POSIX.1): Characters that Cause Signals.

`int VKILL`

  `termios.h` (POSIX.1): Characters for Input Editing.

`int VLNEXT`

  `termios.h` (BSD): Other Special Characters.

`int VMIN`

  `termios.h` (POSIX.1): Noncanonical Input.

`int VQUIT`

  `termios.h` (POSIX.1): Characters that Cause Signals.

`int VREPRINT`

  `termios.h` (BSD): Characters for Input Editing.

`int VSTART`

  `termios.h` (POSIX.1): Special Characters for Flow Control.

`int VSTATUS`

  `termios.h` (BSD): Other Special Characters.

`int VSTOP`

  `termios.h` (POSIX.1): Special Characters for Flow Control.

`int VSUSP`

  `termios.h` (POSIX.1): Characters that Cause Signals.

`int VTIME`

  `termios.h` (POSIX.1): Noncanonical Input.

`int VWERASE`

  `termios.h` (BSD): Characters for Input Editing.

`WCHAR_MAX`

  `limits.h` (GNU): Range of an Integer Type.

`wint_t WCHAR_MAX`

  `wchar.h` (ISO): Introduction to Extended Characters.

`wint_t WCHAR_MIN`

  `wchar.h` (ISO): Introduction to Extended Characters.

`WCHAR_WIDTH`

  `stdint.h` (ISO): Width of an Integer Type.

`int WCOREDUMP (int status)`

  `sys/wait.h` (POSIX.1-2024): Process Completion Status.

`int WEOF`

  `wchar.h` (ISO): End-Of-File and Errors.

`wint_t WEOF`

  `wchar.h` (ISO): Introduction to Extended Characters.

`int WEXITSTATUS (int status)`

  `sys/wait.h` (POSIX.1): Process Completion Status.

`int WIFEXITED (int status)`

  `sys/wait.h` (POSIX.1): Process Completion Status.

`int WIFSIGNALED (int status)`

  `sys/wait.h` (POSIX.1): Process Completion Status.

`int WIFSTOPPED (int status)`

  `sys/wait.h` (POSIX.1): Process Completion Status.

`WINT_WIDTH`

  `stdint.h` (ISO): Width of an Integer Type.

`WRDE_APPEND`

  `wordexp.h` (POSIX.2): Flags for Word Expansion.

`WRDE_BADCHAR`

  `wordexp.h` (POSIX.2): Calling `wordexp`.

`WRDE_BADVAL`

  `wordexp.h` (POSIX.2): Calling `wordexp`.

`WRDE_CMDSUB`

  `wordexp.h` (POSIX.2): Calling `wordexp`.

`WRDE_DOOFFS`

  `wordexp.h` (POSIX.2): Flags for Word Expansion.

`WRDE_NOCMD`

  `wordexp.h` (POSIX.2): Flags for Word Expansion.

`WRDE_NOSPACE`

  `wordexp.h` (POSIX.2): Calling `wordexp`.

`WRDE_REUSE`

  `wordexp.h` (POSIX.2): Flags for Word Expansion.

`WRDE_SHOWERR`

  `wordexp.h` (POSIX.2): Flags for Word Expansion.

`WRDE_SYNTAX`

  `wordexp.h` (POSIX.2): Calling `wordexp`.

`WRDE_UNDEF`

  `wordexp.h` (POSIX.2): Flags for Word Expansion.

`int WSTOPSIG (int status)`

  `sys/wait.h` (POSIX.1): Process Completion Status.

`int WTERMSIG (int status)`

  `sys/wait.h` (POSIX.1): Process Completion Status.

`int W_OK`

  `unistd.h` (POSIX.1): Testing Permission to Access a File.

`int X_OK`

  `unistd.h` (POSIX.1): Testing Permission to Access a File.

`_ATFILE_SOURCE`

  no header (GNU): Feature Test Macros.

`_CS_LFS64_CFLAGS`

  `unistd.h` (Unix98): String-Valued Parameters.

`_CS_LFS64_LDFLAGS`

  `unistd.h` (Unix98): String-Valued Parameters.

`_CS_LFS64_LIBS`

  `unistd.h` (Unix98): String-Valued Parameters.

`_CS_LFS64_LINTFLAGS`

  `unistd.h` (Unix98): String-Valued Parameters.

`_CS_LFS_CFLAGS`

  `unistd.h` (Unix98): String-Valued Parameters.

`_CS_LFS_LDFLAGS`

  `unistd.h` (Unix98): String-Valued Parameters.

`_CS_LFS_LIBS`

  `unistd.h` (Unix98): String-Valued Parameters.

`_CS_LFS_LINTFLAGS`

  `unistd.h` (Unix98): String-Valued Parameters.

`_CS_PATH`

  `unistd.h` (POSIX.2): String-Valued Parameters.

`const float complex _Complex_I`

  `complex.h` (C99): Complex Numbers.

`_DEFAULT_SOURCE`

  no header (GNU): Feature Test Macros.

`_DYNAMIC_STACK_SIZE_SOURCE`

  no header (GNU): Feature Test Macros.

`void _Exit (int status)`

  `stdlib.h` (ISO): Termination Internals.

`_FILE_OFFSET_BITS`

  no header (X/Open): Feature Test Macros.

`_FORTIFY_SOURCE`

  no header (GNU): Feature Test Macros.

`pid_t _Fork (void)`

  `unistd.h` (POSIX.1-2024): Creating a Process.

`_GNU_SOURCE`

  no header (GNU): Feature Test Macros.

`int _IOFBF`

  `stdio.h` (ISO): Controlling Which Kind of Buffering.

`int _IOLBF`

  `stdio.h` (ISO): Controlling Which Kind of Buffering.

`int _IONBF`

  `stdio.h` (ISO): Controlling Which Kind of Buffering.

`_ISOC11_SOURCE`

  no header (C11): Feature Test Macros.

`_ISOC23_SOURCE`

  no header (C23): Feature Test Macros.

`_ISOC2Y_SOURCE`

  no header (C2Y): Feature Test Macros.

`_ISOC99_SOURCE`

  no header (GNU): Feature Test Macros.

`_LARGEFILE64_SOURCE`

  no header (X/Open): Feature Test Macros.

`_LARGEFILE_SOURCE`

  no header (X/Open): Feature Test Macros.

`_PC_ASYNC_IO`

  `unistd.h` (POSIX.1): Using `pathconf`.

`_PC_CHOWN_RESTRICTED`

  `unistd.h` (POSIX.1): Using `pathconf`.

`_PC_FILESIZEBITS`

  `unistd.h` (LFS): Using `pathconf`.

`_PC_LINK_MAX`

  `unistd.h` (POSIX.1): Using `pathconf`.

`_PC_MAX_CANON`

  `unistd.h` (POSIX.1): Using `pathconf`.

`_PC_MAX_INPUT`

  `unistd.h` (POSIX.1): Using `pathconf`.

`_PC_NAME_MAX`

  `unistd.h` (POSIX.1): Using `pathconf`.

`_PC_NO_TRUNC`

  `unistd.h` (POSIX.1): Using `pathconf`.

`_PC_PATH_MAX`

  `unistd.h` (POSIX.1): Using `pathconf`.

`_PC_PIPE_BUF`

  `unistd.h` (POSIX.1): Using `pathconf`.

`_PC_PRIO_IO`

  `unistd.h` (POSIX.1): Using `pathconf`.

`_PC_REC_INCR_XFER_SIZE`

  `unistd.h` (POSIX.1): Using `pathconf`.

`_PC_REC_MAX_XFER_SIZE`

  `unistd.h` (POSIX.1): Using `pathconf`.

`_PC_REC_MIN_XFER_SIZE`

  `unistd.h` (POSIX.1): Using `pathconf`.

`_PC_REC_XFER_ALIGN`

  `unistd.h` (POSIX.1): Using `pathconf`.

`_PC_SYNC_IO`

  `unistd.h` (POSIX.1): Using `pathconf`.

`_PC_VDISABLE`

  `unistd.h` (POSIX.1): Using `pathconf`.

`_POSIX2_BC_BASE_MAX`

  `limits.h` (POSIX.2): Minimum Values for Utility Limits.

`_POSIX2_BC_DIM_MAX`

  `limits.h` (POSIX.2): Minimum Values for Utility Limits.

`_POSIX2_BC_SCALE_MAX`

  `limits.h` (POSIX.2): Minimum Values for Utility Limits.

`_POSIX2_BC_STRING_MAX`

  `limits.h` (POSIX.2): Minimum Values for Utility Limits.

`_POSIX2_COLL_WEIGHTS_MAX`

  `limits.h` (POSIX.2): Minimum Values for Utility Limits.

`int _POSIX2_C_DEV`

  `unistd.h` (POSIX.2): Overall System Options.

`long int _POSIX2_C_VERSION`

  `unistd.h` (POSIX.2): Which Version of POSIX is Supported.

`_POSIX2_EQUIV_CLASS_MAX`

  `limits.h` (POSIX.2): Minimum Values for Utility Limits.

`_POSIX2_EXPR_NEST_MAX`

  `limits.h` (POSIX.2): Minimum Values for Utility Limits.

`int _POSIX2_FORT_DEV`

  `unistd.h` (POSIX.2): Overall System Options.

`int _POSIX2_FORT_RUN`

  `unistd.h` (POSIX.2): Overall System Options.

`_POSIX2_LINE_MAX`

  `limits.h` (POSIX.2): Minimum Values for Utility Limits.

`int _POSIX2_LOCALEDEF`

  `unistd.h` (POSIX.2): Overall System Options.

`_POSIX2_RE_DUP_MAX`

  `limits.h` (POSIX.2): Minimum Values for General Capacity Limits.

`int _POSIX2_SW_DEV`

  `unistd.h` (POSIX.2): Overall System Options.

`_POSIX_AIO_LISTIO_MAX`

  `limits.h` (POSIX.1): Minimum Values for General Capacity Limits.

`_POSIX_AIO_MAX`

  `limits.h` (POSIX.1): Minimum Values for General Capacity Limits.

`_POSIX_ARG_MAX`

  `limits.h` (POSIX.1): Minimum Values for General Capacity Limits.

`_POSIX_CHILD_MAX`

  `limits.h` (POSIX.1): Minimum Values for General Capacity Limits.

`int _POSIX_CHOWN_RESTRICTED`

  `unistd.h` (POSIX.1): Optional Features in File Support.

`_POSIX_C_SOURCE`

  no header (POSIX.2): Feature Test Macros.

`int _POSIX_JOB_CONTROL`

  `unistd.h` (POSIX.1): Overall System Options.

`_POSIX_LINK_MAX`

  `limits.h` (POSIX.1): Minimum Values for File System Limits.

`_POSIX_MAX_CANON`

  `limits.h` (POSIX.1): Minimum Values for File System Limits.

`_POSIX_MAX_INPUT`

  `limits.h` (POSIX.1): Minimum Values for File System Limits.

`_POSIX_NAME_MAX`

  `limits.h` (POSIX.1): Minimum Values for File System Limits.

`_POSIX_NGROUPS_MAX`

  `limits.h` (POSIX.1): Minimum Values for General Capacity Limits.

`int _POSIX_NO_TRUNC`

  `unistd.h` (POSIX.1): Optional Features in File Support.

`_POSIX_OPEN_MAX`

  `limits.h` (POSIX.1): Minimum Values for General Capacity Limits.

`_POSIX_PATH_MAX`

  `limits.h` (POSIX.1): Minimum Values for File System Limits.

`_POSIX_PIPE_BUF`

  `limits.h` (POSIX.1): Minimum Values for File System Limits.

`int _POSIX_SAVED_IDS`

  `unistd.h` (POSIX.1): Overall System Options.

`_POSIX_SOURCE`

  no header (POSIX.1): Feature Test Macros.

`_POSIX_SSIZE_MAX`

  `limits.h` (POSIX.1): Minimum Values for General Capacity Limits.

`_POSIX_STREAM_MAX`

  `limits.h` (POSIX.1): Minimum Values for General Capacity Limits.

`_POSIX_TZNAME_MAX`

  `limits.h` (POSIX.1): Minimum Values for General Capacity Limits.

`unsigned char _POSIX_VDISABLE`

  `unistd.h` (POSIX.1): Optional Features in File Support.

`long int _POSIX_VERSION`

  `unistd.h` (POSIX.1): Which Version of POSIX is Supported.

`_REENTRANT`

  no header (Obsolete): Feature Test Macros.

`_SC_2_C_DEV`

  `unistd.h` (POSIX.2): Constants for `sysconf` Parameters.

`_SC_2_FORT_DEV`

  `unistd.h` (POSIX.2): Constants for `sysconf` Parameters.

`_SC_2_FORT_RUN`

  `unistd.h` (POSIX.2): Constants for `sysconf` Parameters.

`_SC_2_LOCALEDEF`

  `unistd.h` (POSIX.2): Constants for `sysconf` Parameters.

`_SC_2_SW_DEV`

  `unistd.h` (POSIX.2): Constants for `sysconf` Parameters.

`_SC_2_VERSION`

  `unistd.h` (POSIX.2): Constants for `sysconf` Parameters.

`_SC_AIO_LISTIO_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_AIO_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_AIO_PRIO_DELTA_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_ARG_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_ASYNCHRONOUS_IO`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_ATEXIT_MAX`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_AVPHYS_PAGES`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_BC_BASE_MAX`

  `unistd.h` (POSIX.2): Constants for `sysconf` Parameters.

`_SC_BC_DIM_MAX`

  `unistd.h` (POSIX.2): Constants for `sysconf` Parameters.

`_SC_BC_SCALE_MAX`

  `unistd.h` (POSIX.2): Constants for `sysconf` Parameters.

`_SC_BC_STRING_MAX`

  `unistd.h` (POSIX.2): Constants for `sysconf` Parameters.

`_SC_CHARCLASS_NAME_MAX`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_CHAR_BIT`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_CHAR_MAX`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_CHAR_MIN`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_CHILD_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_CLK_TCK`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_COLL_WEIGHTS_MAX`

  `unistd.h` (POSIX.2): Constants for `sysconf` Parameters.

`_SC_DELAYTIMER_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_EQUIV_CLASS_MAX`

  `unistd.h` (POSIX.2): Constants for `sysconf` Parameters.

`_SC_EXPR_NEST_MAX`

  `unistd.h` (POSIX.2): Constants for `sysconf` Parameters.

`_SC_FSYNC`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_GETGR_R_SIZE_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_GETPW_R_SIZE_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_INT_MAX`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_INT_MIN`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_JOB_CONTROL`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_LEVEL1_DCACHE_ASSOC`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_LEVEL1_DCACHE_LINESIZE`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_LEVEL1_DCACHE_SIZE`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_LEVEL1_ICACHE_ASSOC`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_LEVEL1_ICACHE_LINESIZE`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_LEVEL1_ICACHE_SIZE`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_LEVEL2_CACHE_ASSOC`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_LEVEL2_CACHE_LINESIZE`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_LEVEL2_CACHE_SIZE`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_LEVEL3_CACHE_ASSOC`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_LEVEL3_CACHE_LINESIZE`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_LEVEL3_CACHE_SIZE`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_LEVEL4_CACHE_ASSOC`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_LEVEL4_CACHE_LINESIZE`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_LEVEL4_CACHE_SIZE`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_LINE_MAX`

  `unistd.h` (POSIX.2): Constants for `sysconf` Parameters.

`_SC_LOGIN_NAME_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_LONG_BIT`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_MAPPED_FILES`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_MB_LEN_MAX`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_MEMLOCK`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_MEMLOCK_RANGE`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_MEMORY_PROTECTION`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_MESSAGE_PASSING`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_MINSIGSTKSZ`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_MQ_OPEN_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_MQ_PRIO_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_NGROUPS_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_NL_ARGMAX`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_NL_LANGMAX`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_NL_MSGMAX`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_NL_NMAX`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_NL_SETMAX`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_NL_TEXTMAX`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_NPROCESSORS_CONF`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_NPROCESSORS_ONLN`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_NZERO`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_OPEN_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_PAGESIZE`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_PHYS_PAGES`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_PII`

  `unistd.h` (POSIX.1g): Constants for `sysconf` Parameters.

`_SC_PII_INTERNET`

  `unistd.h` (POSIX.1g): Constants for `sysconf` Parameters.

`_SC_PII_INTERNET_DGRAM`

  `unistd.h` (POSIX.1g): Constants for `sysconf` Parameters.

`_SC_PII_INTERNET_STREAM`

  `unistd.h` (POSIX.1g): Constants for `sysconf` Parameters.

`_SC_PII_OSI`

  `unistd.h` (POSIX.1g): Constants for `sysconf` Parameters.

`_SC_PII_OSI_CLTS`

  `unistd.h` (POSIX.1g): Constants for `sysconf` Parameters.

`_SC_PII_OSI_COTS`

  `unistd.h` (POSIX.1g): Constants for `sysconf` Parameters.

`_SC_PII_OSI_M`

  `unistd.h` (POSIX.1g): Constants for `sysconf` Parameters.

`_SC_PII_SOCKET`

  `unistd.h` (POSIX.1g): Constants for `sysconf` Parameters.

`_SC_PII_XTI`

  `unistd.h` (POSIX.1g): Constants for `sysconf` Parameters.

`_SC_PRIORITIZED_IO`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_PRIORITY_SCHEDULING`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_REALTIME_SIGNALS`

  `unistdh.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_RTSIG_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_SAVED_IDS`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_SCHAR_MAX`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_SCHAR_MIN`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_SELECT`

  `unistd.h` (POSIX.1g): Constants for `sysconf` Parameters.

`_SC_SEMAPHORES`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_SEM_NSEMS_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_SEM_VALUE_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_SHARED_MEMORY_OBJECTS`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_SHRT_MAX`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_SHRT_MIN`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_SIGQUEUE_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_SIGSTKSZ`

  `unistd.h` (GNU): Constants for `sysconf` Parameters.

`_SC_SSIZE_MAX`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_STREAM_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_SYNCHRONIZED_IO`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_THREADS`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_THREAD_ATTR_STACKADDR`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_THREAD_ATTR_STACKSIZE`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_THREAD_DESTRUCTOR_ITERATIONS`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_THREAD_KEYS_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_THREAD_PRIORITY_SCHEDULING`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_THREAD_PRIO_INHERIT`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_THREAD_PRIO_PROTECT`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_THREAD_PROCESS_SHARED`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_THREAD_SAFE_FUNCTIONS`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_THREAD_STACK_MIN`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_THREAD_THREADS_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_TIMERS`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_TIMER_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_TTY_NAME_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_TZNAME_MAX`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

`_SC_T_IOV_MAX`

  `unistd.h` (POSIX.1g): Constants for `sysconf` Parameters.

`_SC_UCHAR_MAX`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_UINT_MAX`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_UIO_MAXIOV`

  `unistd.h` (POSIX.1g): Constants for `sysconf` Parameters.

`_SC_ULONG_MAX`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_USHRT_MAX`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_VERSION`

  `unistd.h` (POSIX.1): Constants for `sysconf` Parameters.

  `unistd.h` (POSIX.2): Constants for `sysconf` Parameters.

`_SC_WORD_BIT`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_XOPEN_CRYPT`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_XOPEN_ENH_I18N`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_XOPEN_LEGACY`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_XOPEN_REALTIME`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_XOPEN_REALTIME_THREADS`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_XOPEN_SHM`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_XOPEN_UNIX`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_XOPEN_VERSION`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_XOPEN_XCU_VERSION`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_XOPEN_XPG2`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_XOPEN_XPG3`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_SC_XOPEN_XPG4`

  `unistd.h` (X/Open): Constants for `sysconf` Parameters.

`_THREAD_SAFE`

  no header (Obsolete): Feature Test Macros.

`_XOPEN_SOURCE`

  no header (X/Open): Feature Test Macros.

`_XOPEN_SOURCE_EXTENDED`

  no header (X/Open): Feature Test Macros.

`__STDC_WANT_IEC_60559_BFP_EXT__`

  no header (ISO): Feature Test Macros.

`__STDC_WANT_IEC_60559_EXT__`

  no header (ISO): Feature Test Macros.

`__STDC_WANT_IEC_60559_FUNCS_EXT__`

  no header (ISO): Feature Test Macros.

`__STDC_WANT_IEC_60559_TYPES_EXT__`

  no header (ISO): Feature Test Macros.

`__STDC_WANT_LIB_EXT2__`

  no header (ISO): Feature Test Macros.

`size_t __fbufsize (FILE *stream)`

  `stdio_ext.h` (GNU): Controlling Which Kind of Buffering.

`int __flbf (FILE *stream)`

  `stdio_ext.h` (GNU): Controlling Which Kind of Buffering.

`size_t __fpending (FILE *stream)`

  `stdio_ext.h` (GNU): Controlling Which Kind of Buffering.

`void __fpurge (FILE *stream)`

  `stdio_ext.h` (GNU): Flushing Buffers.

`int __freadable (FILE *stream)`

  `stdio_ext.h` (GNU): Opening Streams.

`int __freading (FILE *stream)`

  `stdio_ext.h` (GNU): Opening Streams.

`int __fsetlocking (FILE *stream, int type)`

  `stdio_ext.h` (GNU): Streams and Threads.

`__ftw64_func_t`

  `ftw.h` (GNU): Working with Directory Trees.

`__ftw_func_t`

  `ftw.h` (GNU): Working with Directory Trees.

`int __fwritable (FILE *stream)`

  `stdio_ext.h` (GNU): Opening Streams.

`int __fwriting (FILE *stream)`

  `stdio_ext.h` (GNU): Opening Streams.

`void (*__gconv_end_fct) (struct gconv_step *)`

  `gconv.h` (GNU): The `iconv` Implementation in the GNU C Library.

`int (*__gconv_fct) (struct __gconv_step *, struct __gconv_step_data *, const char **, const char *, size_t *, int)`

  `gconv.h` (GNU): The `iconv` Implementation in the GNU C Library.

`int (*__gconv_init_fct) (struct __gconv_step *)`

  `gconv.h` (GNU): The `iconv` Implementation in the GNU C Library.

`struct __gconv_step`

  `gconv.h` (GNU): The `iconv` Implementation in the GNU C Library.

`struct __gconv_step_data`

  `gconv.h` (GNU): The `iconv` Implementation in the GNU C Library.

`char __libc_single_threaded`

  `sys/single_threaded.h` (GNU): Detecting Single-Threaded Execution.

`__nftw64_func_t`

  `ftw.h` (GNU): Working with Directory Trees.

`__nftw_func_t`

  `ftw.h` (GNU): Working with Directory Trees.

`unsigned int __rseq_flags`

  `sys/rseq.h` (Linux): Restartable Sequences.

`ptrdiff_t __rseq_offset`

  `sys/rseq.h` (Linux): Restartable Sequences.

`unsigned int __rseq_size`

  `sys/rseq.h` (Linux): Restartable Sequences.

`void __va_copy (va_list dest, va_list src)`

  `stdarg.h` (GNU): Argument Access Macros.

`int _dl_find_object (void *address, struct dl_find_object *result)`

  `dlfcn.h` (GNU): Dynamic Linker Introspection.

`void _exit (int status)`

  `unistd.h` (POSIX.1): Termination Internals.

`void _flushlbf (void)`

  `stdio_ext.h` (GNU): Flushing Buffers.

`int _tolower (int c)`

  `ctype.h` (SVID): Case Conversion.

`int _toupper (int c)`

  `ctype.h` (SVID): Case Conversion.

`long int a64l (const char *string)`

  `stdlib.h` (XPG): Encode Binary Data.

`void abort (void)`

  `stdlib.h` (ISO): Aborting a Program.

`int abs (int number)`

  `stdlib.h` (ISO): Absolute Value.

`int accept (int socket, struct sockaddr *addr, socklen_t *length_ptr)`

  `sys/socket.h` (BSD): Accepting Connections.

`int access (const char *filename, int how)`

  `unistd.h` (POSIX.1): Testing Permission to Access a File.

`double acos (double x)`

  `math.h` (ISO): Inverse Trigonometric Functions.

`float acosf (float x)`

  `math.h` (ISO): Inverse Trigonometric Functions.

`_FloatN acosfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Inverse Trigonometric Functions.

`_FloatNx acosfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Inverse Trigonometric Functions.

`double acosh (double x)`

  `math.h` (ISO): Hyperbolic Functions.

`float acoshf (float x)`

  `math.h` (ISO): Hyperbolic Functions.

`_FloatN acoshfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Hyperbolic Functions.

`_FloatNx acoshfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Hyperbolic Functions.

`long double acoshl (long double x)`

  `math.h` (ISO): Hyperbolic Functions.

`long double acosl (long double x)`

  `math.h` (ISO): Inverse Trigonometric Functions.

`double acospi (double x)`

  `math.h` (TS 18661-4:2015): Inverse Trigonometric Functions.

`float acospif (float x)`

  `math.h` (TS 18661-4:2015): Inverse Trigonometric Functions.

`_FloatN acospifN (_FloatN x)`

  `math.h` (TS 18661-4:2015): Inverse Trigonometric Functions.

`_FloatNx acospifNx (_FloatNx x)`

  `math.h` (TS 18661-4:2015): Inverse Trigonometric Functions.

`long double acospil (long double x)`

  `math.h` (TS 18661-4:2015): Inverse Trigonometric Functions.

`int addmntent (FILE *stream, const struct mntent *mnt)`

  `mntent.h` (BSD): The `mtab` file.

`int adjtime (const struct timeval *delta, struct timeval *olddelta)`

  `sys/time.h` (BSD): Setting and Adjusting the Time.

`int adjtimex (struct timex *timex)`

  `sys/timex.h` (GNU): Setting and Adjusting the Time.

`int aio_cancel (int fildes, struct aiocb *aiocbp)`

  `aio.h` (POSIX.1b): Cancellation of AIO Operations.

`int aio_cancel64 (int fildes, struct aiocb64 *aiocbp)`

  `aio.h` (Unix98): Cancellation of AIO Operations.

`int aio_error (const struct aiocb *aiocbp)`

  `aio.h` (POSIX.1b): Getting the Status of AIO Operations.

`int aio_error64 (const struct aiocb64 *aiocbp)`

  `aio.h` (Unix98): Getting the Status of AIO Operations.

`int aio_fsync (int op, struct aiocb *aiocbp)`

  `aio.h` (POSIX.1b): Getting into a Consistent State.

`int aio_fsync64 (int op, struct aiocb64 *aiocbp)`

  `aio.h` (Unix98): Getting into a Consistent State.

`void aio_init (const struct aioinit *init)`

  `aio.h` (GNU): How to optimize the AIO implementation.

`int aio_read (struct aiocb *aiocbp)`

  `aio.h` (POSIX.1b): Asynchronous Read and Write Operations.

`int aio_read64 (struct aiocb64 *aiocbp)`

  `aio.h` (Unix98): Asynchronous Read and Write Operations.

`ssize_t aio_return (struct aiocb *aiocbp)`

  `aio.h` (POSIX.1b): Getting the Status of AIO Operations.

`ssize_t aio_return64 (struct aiocb64 *aiocbp)`

  `aio.h` (Unix98): Getting the Status of AIO Operations.

`int aio_suspend (const struct aiocb *const list[], int nent, const struct timespec *timeout)`

  `aio.h` (POSIX.1b): Getting into a Consistent State.

`int aio_suspend64 (const struct aiocb64 *const list[], int nent, const struct timespec *timeout)`

  `aio.h` (Unix98): Getting into a Consistent State.

`int aio_write (struct aiocb *aiocbp)`

  `aio.h` (POSIX.1b): Asynchronous Read and Write Operations.

`int aio_write64 (struct aiocb64 *aiocbp)`

  `aio.h` (Unix98): Asynchronous Read and Write Operations.

`struct aiocb`

  `aio.h` (POSIX.1b): Perform I/O Operations in Parallel.

`struct aiocb64`

  `aio.h` (POSIX.1b): Perform I/O Operations in Parallel.

`struct aioinit`

  `aio.h` (GNU): How to optimize the AIO implementation.

`unsigned int alarm (unsigned int seconds)`

  `unistd.h` (POSIX.1): Setting an Alarm.

`void * aligned_alloc (size_t alignment, size_t size)`

  `stdlib.h` (???): Allocating Aligned Memory Blocks.

`void * alloca (size_t size)`

  `stdlib.h` (GNU): Automatic Storage with Variable Size.

  `stdlib.h` (BSD): Automatic Storage with Variable Size.

`int alphasort (const struct dirent **a, const struct dirent **b)`

  `dirent.h` (BSD): Scanning the Content of a Directory.

  `dirent.h` (SVID): Scanning the Content of a Directory.

`int alphasort64 (const struct dirent64 **a, const struct dirent **b)`

  `dirent.h` (GNU): Scanning the Content of a Directory.

`uint32_t arc4random (void)`

  `stdlib.h` (BSD): High Quality Random Number Functions.

`void arc4random_buf (void *buffer, size_t length)`

  `stdlib.h` (BSD): High Quality Random Number Functions.

`uint32_t arc4random_uniform (uint32_t upper_bound)`

  `stdlib.h` (BSD): High Quality Random Number Functions.

`struct argp`

  `argp.h` (GNU): Specifying Argp Parsers.

`struct argp_child`

  `argp.h` (GNU): Combining Multiple Argp Parsers.

`error_t argp_err_exit_status`

  `argp.h` (GNU): Argp Global Variables.

`void argp_error (const struct argp_state *state, const char *fmt, …)`

  `argp.h` (GNU): Functions For Use in Argp Parsers.

`void argp_failure (const struct argp_state *state, int status, int errnum, const char *fmt, …)`

  `argp.h` (GNU): Functions For Use in Argp Parsers.

`void argp_help (const struct argp *argp, FILE *stream, unsigned flags, char *name)`

  `argp.h` (GNU): The `argp_help` Function.

`struct argp_option`

  `argp.h` (GNU): Specifying Options in an Argp Parser.

`error_t argp_parse (const struct argp *argp, int argc, char **argv, unsigned flags, int *arg_index, void *input)`

  `argp.h` (GNU): Parsing Program Options with Argp.

`const char * argp_program_bug_address`

  `argp.h` (GNU): Argp Global Variables.

`const char * argp_program_version`

  `argp.h` (GNU): Argp Global Variables.

`argp_program_version_hook`

  `argp.h` (GNU): Argp Global Variables.

`struct argp_state`

  `argp.h` (GNU): Argp Parsing State.

`void argp_state_help (const struct argp_state *state, FILE *stream, unsigned flags)`

  `argp.h` (GNU): Functions For Use in Argp Parsers.

`void argp_usage (const struct argp_state *state)`

  `argp.h` (GNU): Functions For Use in Argp Parsers.

`error_t argz_add (char **argz, size_t *argz_len, const char *str)`

  `argz.h` (GNU): Argz Functions.

`error_t argz_add_sep (char **argz, size_t *argz_len, const char *str, int delim)`

  `argz.h` (GNU): Argz Functions.

`error_t argz_append (char **argz, size_t *argz_len, const char *buf, size_t buf_len)`

  `argz.h` (GNU): Argz Functions.

`size_t argz_count (const char *argz, size_t argz_len)`

  `argz.h` (GNU): Argz Functions.

`error_t argz_create (char *const argv[], char **argz, size_t *argz_len)`

  `argz.h` (GNU): Argz Functions.

`error_t argz_create_sep (const char *string, int sep, char **argz, size_t *argz_len)`

  `argz.h` (GNU): Argz Functions.

`void argz_delete (char **argz, size_t *argz_len, char *entry)`

  `argz.h` (GNU): Argz Functions.

`void argz_extract (const char *argz, size_t argz_len, char **argv)`

  `argz.h` (GNU): Argz Functions.

`error_t argz_insert (char **argz, size_t *argz_len, char *before, const char *entry)`

  `argz.h` (GNU): Argz Functions.

`char * argz_next (const char *argz, size_t argz_len, const char *entry)`

  `argz.h` (GNU): Argz Functions.

`error_t argz_replace (char **argz, size_t *argz_len, const char *str, const char *with, unsigned *replace_count)`

  `argz.h` (GNU): Argz Functions.

`void argz_stringify (char *argz, size_t len, int sep)`

  `argz.h` (GNU): Argz Functions.

`char * asctime (const struct tm *brokentime)`

  `time.h` (ISO): Formatting Calendar Time.

`char * asctime_r (const struct tm *brokentime, char *buffer)`

  `time.h` (???): Formatting Calendar Time.

`double asin (double x)`

  `math.h` (ISO): Inverse Trigonometric Functions.

`float asinf (float x)`

  `math.h` (ISO): Inverse Trigonometric Functions.

`_FloatN asinfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Inverse Trigonometric Functions.

`_FloatNx asinfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Inverse Trigonometric Functions.

`double asinh (double x)`

  `math.h` (ISO): Hyperbolic Functions.

`float asinhf (float x)`

  `math.h` (ISO): Hyperbolic Functions.

`_FloatN asinhfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Hyperbolic Functions.

`_FloatNx asinhfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Hyperbolic Functions.

`long double asinhl (long double x)`

  `math.h` (ISO): Hyperbolic Functions.

`long double asinl (long double x)`

  `math.h` (ISO): Inverse Trigonometric Functions.

`double asinpi (double x)`

  `math.h` (TS 18661-4:2015): Inverse Trigonometric Functions.

`float asinpif (float x)`

  `math.h` (TS 18661-4:2015): Inverse Trigonometric Functions.

`_FloatN asinpifN (_FloatN x)`

  `math.h` (TS 18661-4:2015): Inverse Trigonometric Functions.

`_FloatNx asinpifNx (_FloatNx x)`

  `math.h` (TS 18661-4:2015): Inverse Trigonometric Functions.

`long double asinpil (long double x)`

  `math.h` (TS 18661-4:2015): Inverse Trigonometric Functions.

`int asprintf (char **ptr, const char *template, …)`

  `stdio.h` (GNU): Dynamically Allocating Formatted Output.

`void assert (int expression)`

  `assert.h` (ISO): Explicitly Checking Internal Consistency.

`void assert_perror (int errnum)`

  `assert.h` (GNU): Explicitly Checking Internal Consistency.

`double atan (double x)`

  `math.h` (ISO): Inverse Trigonometric Functions.

`double atan2 (double y, double x)`

  `math.h` (ISO): Inverse Trigonometric Functions.

`float atan2f (float y, float x)`

  `math.h` (ISO): Inverse Trigonometric Functions.

`_FloatN atan2fN (_FloatN y, _FloatN x)`

  `math.h` (TS 18661-3:2015): Inverse Trigonometric Functions.

`_FloatNx atan2fNx (_FloatNx y, _FloatNx x)`

  `math.h` (TS 18661-3:2015): Inverse Trigonometric Functions.

`long double atan2l (long double y, long double x)`

  `math.h` (ISO): Inverse Trigonometric Functions.

`double atan2pi (double y, double x)`

  `math.h` (TS 18661-4:2015): Inverse Trigonometric Functions.

`float atan2pif (float y, float x)`

  `math.h` (TS 18661-4:2015): Inverse Trigonometric Functions.

`_FloatN atan2pifN (_FloatN y, _FloatN x)`

  `math.h` (TS 18661-4:2015): Inverse Trigonometric Functions.

`_FloatNx atan2pifNx (_FloatNx y, _FloatNx x)`

  `math.h` (TS 18661-4:2015): Inverse Trigonometric Functions.

`long double atan2pil (long double y, long double x)`

  `math.h` (TS 18661-4:2015): Inverse Trigonometric Functions.

`float atanf (float x)`

  `math.h` (ISO): Inverse Trigonometric Functions.

`_FloatN atanfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Inverse Trigonometric Functions.

`_FloatNx atanfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Inverse Trigonometric Functions.

`double atanh (double x)`

  `math.h` (ISO): Hyperbolic Functions.

`float atanhf (float x)`

  `math.h` (ISO): Hyperbolic Functions.

`_FloatN atanhfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Hyperbolic Functions.

`_FloatNx atanhfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Hyperbolic Functions.

`long double atanhl (long double x)`

  `math.h` (ISO): Hyperbolic Functions.

`long double atanl (long double x)`

  `math.h` (ISO): Inverse Trigonometric Functions.

`double atanpi (double x)`

  `math.h` (TS 18661-4:2015): Inverse Trigonometric Functions.

`float atanpif (float x)`

  `math.h` (TS 18661-4:2015): Inverse Trigonometric Functions.

`_FloatN atanpifN (_FloatN x)`

  `math.h` (TS 18661-4:2015): Inverse Trigonometric Functions.

`_FloatNx atanpifNx (_FloatNx x)`

  `math.h` (TS 18661-4:2015): Inverse Trigonometric Functions.

`long double atanpil (long double x)`

  `math.h` (TS 18661-4:2015): Inverse Trigonometric Functions.

`int atexit (void (*function) (void))`

  `stdlib.h` (ISO): Cleanups on Exit.

`double atof (const char *string)`

  `stdlib.h` (ISO): Parsing of Floats.

`int atoi (const char *string)`

  `stdlib.h` (ISO): Parsing of Integers.

`long int atol (const char *string)`

  `stdlib.h` (ISO): Parsing of Integers.

`long long int atoll (const char *string)`

  `stdlib.h` (ISO): Parsing of Integers.

`int backtrace (void **buffer, int size)`

  `execinfo.h` (GNU): Backtraces.

`char ** backtrace_symbols (void *const *buffer, int size)`

  `execinfo.h` (GNU): Backtraces.

`void backtrace_symbols_fd (void *const *buffer, int size, int fd)`

  `execinfo.h` (GNU): Backtraces.

`char * basename (char *path)`

  `libgen.h` (XPG): Finding Tokens in a String.

`char * basename (const char *filename)`

  `string.h` (GNU): Finding Tokens in a String.

`baud_t`

  `termios.h` (GNU): Line Speed.

`int bcmp (const void *a1, const void *a2, size_t size)`

  `string.h` (BSD): String/Array Comparison.

`void bcopy (const void *from, void *to, size_t size)`

  `string.h` (BSD): Copying Strings and Arrays.

`int bind (int socket, struct sockaddr *addr, socklen_t length)`

  `sys/socket.h` (BSD): Setting the Address of a Socket.

`char * bind_textdomain_codeset (const char *domainname, const char *codeset)`

  `libintl.h` (POSIX-1.2024): How to specify the output character set `gettext` uses.

`char * bindtextdomain (const char *domainname, const char *dirname)`

  `libintl.h` (POSIX-1.2024): How to determine which catalog to be used.

`blkcnt64_t`

  `sys/types.h` (Unix98): The meaning of the File Attributes.

`blkcnt_t`

  `sys/types.h` (Unix98): The meaning of the File Attributes.

`int brk (void *addr)`

  `unistd.h` (BSD): Resizing the Data Segment.

`void * bsearch (const void *key, const void *array, size_t count, size_t size, comparison_fn_t compare)`

  `stdlib.h` (ISO): Array Search Function.

`wint_t btowc (int c)`

  `wchar.h` (ISO): Converting Single Characters.

`void bzero (void *block, size_t size)`

  `string.h` (BSD): Copying Strings and Arrays.

`double cabs (complex double z)`

  `complex.h` (ISO): Absolute Value.

`float cabsf (complex float z)`

  `complex.h` (ISO): Absolute Value.

`_FloatN cabsfN (complex _FloatN z)`

  `complex.h` (TS 18661-3:2015): Absolute Value.

`_FloatNx cabsfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Absolute Value.

`long double cabsl (complex long double z)`

  `complex.h` (ISO): Absolute Value.

`complex double cacos (complex double z)`

  `complex.h` (ISO): Inverse Trigonometric Functions.

`complex float cacosf (complex float z)`

  `complex.h` (ISO): Inverse Trigonometric Functions.

`complex _FloatN cacosfN (complex _FloatN z)`

  `complex.h` (TS 18661-3:2015): Inverse Trigonometric Functions.

`complex _FloatNx cacosfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Inverse Trigonometric Functions.

`complex double cacosh (complex double z)`

  `complex.h` (ISO): Hyperbolic Functions.

`complex float cacoshf (complex float z)`

  `complex.h` (ISO): Hyperbolic Functions.

`complex _FloatN cacoshfN (complex _FloatN z)`

  `complex.h` (TS 18661-3:2015): Hyperbolic Functions.

`complex _FloatNx cacoshfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Hyperbolic Functions.

`complex long double cacoshl (complex long double z)`

  `complex.h` (ISO): Hyperbolic Functions.

`complex long double cacosl (complex long double z)`

  `complex.h` (ISO): Inverse Trigonometric Functions.

`void call_once (once_flag *flag, void (*func) (void))`

  `threads.h` (C11): Call Once.

`void * calloc (size_t count, size_t eltsize)`

  `malloc.h` (ISO): Allocating Cleared Space.

  `stdlib.h` (ISO): Allocating Cleared Space.

`int canonicalize (double *cx, const double *x)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`char * canonicalize_file_name (const char *name)`

  `stdlib.h` (GNU): Symbolic Links.

`int canonicalizef (float *cx, const float *x)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`int canonicalizefN (_FloatN *cx, const _FloatN *x)`

  `math.h` (TS 18661-3:2015): Setting and modifying single bits of FP values.

`int canonicalizefNx (_FloatNx *cx, const _FloatNx *x)`

  `math.h` (TS 18661-3:2015): Setting and modifying single bits of FP values.

`int canonicalizel (long double *cx, const long double *x)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`double carg (complex double z)`

  `complex.h` (ISO): Projections, Conjugates, and Decomposing of Complex Numbers.

`float cargf (complex float z)`

  `complex.h` (ISO): Projections, Conjugates, and Decomposing of Complex Numbers.

`_FloatN cargfN (complex _FloatN z)`

  `complex.h` (TS 18661-3:2015): Projections, Conjugates, and Decomposing of Complex Numbers.

`_FloatNx cargfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Projections, Conjugates, and Decomposing of Complex Numbers.

`long double cargl (complex long double z)`

  `complex.h` (ISO): Projections, Conjugates, and Decomposing of Complex Numbers.

`complex double casin (complex double z)`

  `complex.h` (ISO): Inverse Trigonometric Functions.

`complex float casinf (complex float z)`

  `complex.h` (ISO): Inverse Trigonometric Functions.

`complex _FloatN casinfN (complex _FloatN z)`

  `complex.h` (TS 18661-3:2015): Inverse Trigonometric Functions.

`complex _FloatNx casinfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Inverse Trigonometric Functions.

`complex double casinh (complex double z)`

  `complex.h` (ISO): Hyperbolic Functions.

`complex float casinhf (complex float z)`

  `complex.h` (ISO): Hyperbolic Functions.

`complex _FloatN casinhfN (complex _FloatN z)`

  `complex.h` (TS 18661-3:2015): Hyperbolic Functions.

`complex _FloatNx casinhfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Hyperbolic Functions.

`complex long double casinhl (complex long double z)`

  `complex.h` (ISO): Hyperbolic Functions.

`complex long double casinl (complex long double z)`

  `complex.h` (ISO): Inverse Trigonometric Functions.

`complex double catan (complex double z)`

  `complex.h` (ISO): Inverse Trigonometric Functions.

`complex float catanf (complex float z)`

  `complex.h` (ISO): Inverse Trigonometric Functions.

`complex _FloatN catanfN (complex _FloatN z)`

  `complex.h` (TS 18661-3:2015): Inverse Trigonometric Functions.

`complex _FloatNx catanfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Inverse Trigonometric Functions.

`complex double catanh (complex double z)`

  `complex.h` (ISO): Hyperbolic Functions.

`complex float catanhf (complex float z)`

  `complex.h` (ISO): Hyperbolic Functions.

`complex _FloatN catanhfN (complex _FloatN z)`

  `complex.h` (TS 18661-3:2015): Hyperbolic Functions.

`complex _FloatNx catanhfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Hyperbolic Functions.

`complex long double catanhl (complex long double z)`

  `complex.h` (ISO): Hyperbolic Functions.

`complex long double catanl (complex long double z)`

  `complex.h` (ISO): Inverse Trigonometric Functions.

`nl_catd catopen (const char *cat_name, int flag)`

  `nl_types.h` (X/Open): The `catgets` function family.

`double cbrt (double x)`

  `math.h` (BSD): Exponentiation and Logarithms.

`float cbrtf (float x)`

  `math.h` (BSD): Exponentiation and Logarithms.

`_FloatN cbrtfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`_FloatNx cbrtfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`long double cbrtl (long double x)`

  `math.h` (BSD): Exponentiation and Logarithms.

`cc_t`

  `termios.h` (POSIX.1): Terminal Mode Data Types.

`complex double ccos (complex double z)`

  `complex.h` (ISO): Trigonometric Functions.

`complex float ccosf (complex float z)`

  `complex.h` (ISO): Trigonometric Functions.

`complex _FloatN ccosfN (complex _FloatN z)`

  `complex.h` (TS 18661-3:2015): Trigonometric Functions.

`complex _FloatNx ccosfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Trigonometric Functions.

`complex double ccosh (complex double z)`

  `complex.h` (ISO): Hyperbolic Functions.

`complex float ccoshf (complex float z)`

  `complex.h` (ISO): Hyperbolic Functions.

`complex _FloatN ccoshfN (complex _FloatN z)`

  `complex.h` (TS 18661-3:2015): Hyperbolic Functions.

`complex _FloatNx ccoshfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Hyperbolic Functions.

`complex long double ccoshl (complex long double z)`

  `complex.h` (ISO): Hyperbolic Functions.

`complex long double ccosl (complex long double z)`

  `complex.h` (ISO): Trigonometric Functions.

`double ceil (double x)`

  `math.h` (ISO): Rounding Functions.

`float ceilf (float x)`

  `math.h` (ISO): Rounding Functions.

`_FloatN ceilfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`_FloatNx ceilfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`long double ceill (long double x)`

  `math.h` (ISO): Rounding Functions.

`complex double cexp (complex double z)`

  `complex.h` (ISO): Exponentiation and Logarithms.

`complex float cexpf (complex float z)`

  `complex.h` (ISO): Exponentiation and Logarithms.

`complex _FloatN cexpfN (complex _FloatN z)`

  `complex.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`complex _FloatNx cexpfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`complex long double cexpl (complex long double z)`

  `complex.h` (ISO): Exponentiation and Logarithms.

`baud_t cfgetibaud (const struct termios *termios-p)`

  `termios.h` (GNU): Line Speed.

`speed_t cfgetispeed (const struct termios *termios-p)`

  `termios.h` (POSIX.1): Line Speed.

`baud_t cfgetobaud (const struct termios *termios-p)`

  `termios.h` (GNU): Line Speed.

`speed_t cfgetospeed (const struct termios *termios-p)`

  `termios.h` (POSIX.1): Line Speed.

`void cfmakeraw (struct termios *termios-p)`

  `termios.h` (BSD): Noncanonical Input.

`int cfsetbaud (struct termios *termios-p, baud_t baud)`

  `termios.h` (GNU): Line Speed.

`int cfsetibaud (struct termios *termios-p, baud_t baud)`

  `termios.h` (GNU): Line Speed.

`int cfsetispeed (struct termios *termios-p, speed_t speed)`

  `termios.h` (POSIX.1): Line Speed.

`int cfsetobaud (struct termios *termios-p, baud_t baud)`

  `termios.h` (GNU): Line Speed.

`int cfsetospeed (struct termios *termios-p, speed_t speed)`

  `termios.h` (POSIX.1): Line Speed.

`int cfsetspeed (struct termios *termios-p, speed_t speed)`

  `termios.h` (BSD): Line Speed.

`int chdir (const char *filename)`

  `unistd.h` (POSIX.1): Working Directory.

`int chmod (const char *filename, mode_t mode)`

  `sys/stat.h` (POSIX.1): Assigning File Permissions.

`int chown (const char *filename, uid_t owner, gid_t group)`

  `unistd.h` (POSIX.1): File Owner.

`double cimag (complex double z)`

  `complex.h` (ISO): Projections, Conjugates, and Decomposing of Complex Numbers.

`float cimagf (complex float z)`

  `complex.h` (ISO): Projections, Conjugates, and Decomposing of Complex Numbers.

`_FloatN cimagfN (complex _FloatN z)`

  `complex.h` (TS 18661-3:2015): Projections, Conjugates, and Decomposing of Complex Numbers.

`_FloatNx cimagfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Projections, Conjugates, and Decomposing of Complex Numbers.

`long double cimagl (complex long double z)`

  `complex.h` (ISO): Projections, Conjugates, and Decomposing of Complex Numbers.

`int clearenv (void)`

  `stdlib.h` (GNU): Environment Access.

`void clearerr (FILE *stream)`

  `stdio.h` (ISO): Recovering from errors.

`void clearerr_unlocked (FILE *stream)`

  `stdio.h` (GNU): Recovering from errors.

`clock_t clock (void)`

  `time.h` (ISO): CPU Time Inquiry.

`int clock_getres (clockid_t clock, struct timespec *res)`

  `time.h` (POSIX.1): Getting the Time.

`int clock_gettime (clockid_t clock, struct timespec *ts)`

  `time.h` (POSIX.1): Getting the Time.

`int clock_nanosleep (clockid_t clock, int flags, const struct timespec *requested_time, struct timespec *remaining_time)`

  `time.h` (POSIX.1-2001): Sleeping.

`int clock_settime (clockid_t clock, const struct timespec *ts)`

  `time.h` (POSIX): Setting and Adjusting the Time.

`clock_t`

  `time.h` (ISO): Time Types.

`clockid_t`

  `time.h` (POSIX.1): Getting the Time.

`complex double clog (complex double z)`

  `complex.h` (ISO): Exponentiation and Logarithms.

`complex double clog10 (complex double z)`

  `complex.h` (GNU): Exponentiation and Logarithms.

`complex float clog10f (complex float z)`

  `complex.h` (GNU): Exponentiation and Logarithms.

`complex _FloatN clog10fN (complex _FloatN z)`

  `complex.h` (GNU): Exponentiation and Logarithms.

`complex _FloatNx clog10fNx (complex _FloatNx z)`

  `complex.h` (GNU): Exponentiation and Logarithms.

`complex long double clog10l (complex long double z)`

  `complex.h` (GNU): Exponentiation and Logarithms.

`complex float clogf (complex float z)`

  `complex.h` (ISO): Exponentiation and Logarithms.

`complex _FloatN clogfN (complex _FloatN z)`

  `complex.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`complex _FloatNx clogfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`complex long double clogl (complex long double z)`

  `complex.h` (ISO): Exponentiation and Logarithms.

`int close (int filedes)`

  `unistd.h` (POSIX.1): Opening and Closing Files.

`int close_range (unsigned int lowfd, unsigned int maxfd, int flags)`

  `unistd.h` (Linux): Opening and Closing Files.

`int closedir (DIR *dirstream)`

  `dirent.h` (POSIX.1): Reading and Closing a Directory Stream.

`void closefrom (int lowfd)`

  `unistd.h` (GNU): Opening and Closing Files.

`void closelog (void)`

  `syslog.h` (BSD): closelog.

`int cnd_broadcast (cnd_t *cond)`

  `threads.h` (C11): Condition Variables.

`void cnd_destroy (cnd_t *cond)`

  `threads.h` (C11): Condition Variables.

`int cnd_init (cnd_t *cond)`

  `threads.h` (C11): Condition Variables.

`int cnd_signal (cnd_t *cond)`

  `threads.h` (C11): Condition Variables.

`cnd_t`

  `threads.h` (C11): Condition Variables.

`int cnd_timedwait (cnd_t *restrict cond, mtx_t *restrict mutex, const struct timespec *restrict time_point)`

  `threads.h` (C11): Condition Variables.

`int cnd_wait (cnd_t *cond, mtx_t *mutex)`

  `threads.h` (C11): Condition Variables.

`double compoundn (double x, long long int power)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`float compoundnf (float x, long long int power)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatN compoundnfN (_FloatN x, long long int power)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatNx compoundnfNx (_FloatNx x, long long int power)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`long double compoundnl (long double x, long long int power)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`size_t confstr (int parameter, char *buf, size_t len)`

  `unistd.h` (POSIX.2): String-Valued Parameters.

`complex double conj (complex double z)`

  `complex.h` (ISO): Projections, Conjugates, and Decomposing of Complex Numbers.

`complex float conjf (complex float z)`

  `complex.h` (ISO): Projections, Conjugates, and Decomposing of Complex Numbers.

`complex _FloatN conjfN (complex _FloatN z)`

  `complex.h` (TS 18661-3:2015): Projections, Conjugates, and Decomposing of Complex Numbers.

`complex _FloatNx conjfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Projections, Conjugates, and Decomposing of Complex Numbers.

`complex long double conjl (complex long double z)`

  `complex.h` (ISO): Projections, Conjugates, and Decomposing of Complex Numbers.

`int connect (int socket, struct sockaddr *addr, socklen_t length)`

  `sys/socket.h` (BSD): Making a Connection.

`cookie_close_function_t`

  `stdio.h` (GNU): Custom Stream Hook Functions.

`cookie_io_functions_t`

  `stdio.h` (GNU): Custom Streams and Cookies.

`cookie_read_function_t`

  `stdio.h` (GNU): Custom Stream Hook Functions.

`cookie_seek_function_t`

  `stdio.h` (GNU): Custom Stream Hook Functions.

`cookie_write_function_t`

  `stdio.h` (GNU): Custom Stream Hook Functions.

`ssize_t copy_file_range (int inputfd, off64_t *inputpos, int outputfd, off64_t *outputpos, ssize_t length, unsigned int flags)`

  `unistd.h` (GNU): Copying data between two files.

`double copysign (double x, double y)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`float copysignf (float x, float y)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`_FloatN copysignfN (_FloatN x, _FloatN y)`

  `math.h` (TS 18661-3:2015): Setting and modifying single bits of FP values.

`_FloatNx copysignfNx (_FloatNx x, _FloatNx y)`

  `math.h` (TS 18661-3:2015): Setting and modifying single bits of FP values.

`long double copysignl (long double x, long double y)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`double cos (double x)`

  `math.h` (ISO): Trigonometric Functions.

`float cosf (float x)`

  `math.h` (ISO): Trigonometric Functions.

`_FloatN cosfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Trigonometric Functions.

`_FloatNx cosfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Trigonometric Functions.

`double cosh (double x)`

  `math.h` (ISO): Hyperbolic Functions.

`float coshf (float x)`

  `math.h` (ISO): Hyperbolic Functions.

`_FloatN coshfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Hyperbolic Functions.

`_FloatNx coshfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Hyperbolic Functions.

`long double coshl (long double x)`

  `math.h` (ISO): Hyperbolic Functions.

`long double cosl (long double x)`

  `math.h` (ISO): Trigonometric Functions.

`double cospi (double x)`

  `math.h` (TS 18661-4:2015): Trigonometric Functions.

`float cospif (float x)`

  `math.h` (TS 18661-4:2015): Trigonometric Functions.

`_FloatN cospifN (_FloatN x)`

  `math.h` (TS 18661-4:2015): Trigonometric Functions.

`_FloatNx cospifNx (_FloatNx x)`

  `math.h` (TS 18661-4:2015): Trigonometric Functions.

`long double cospil (long double x)`

  `math.h` (TS 18661-4:2015): Trigonometric Functions.

`complex double cpow (complex double base, complex double power)`

  `complex.h` (ISO): Exponentiation and Logarithms.

`complex float cpowf (complex float base, complex float power)`

  `complex.h` (ISO): Exponentiation and Logarithms.

`complex _FloatN cpowfN (complex _FloatN base, complex _FloatN power)`

  `complex.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`complex _FloatNx cpowfNx (complex _FloatNx base, complex _FloatNx power)`

  `complex.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`complex long double cpowl (complex long double base, complex long double power)`

  `complex.h` (ISO): Exponentiation and Logarithms.

`complex double cproj (complex double z)`

  `complex.h` (ISO): Projections, Conjugates, and Decomposing of Complex Numbers.

`complex float cprojf (complex float z)`

  `complex.h` (ISO): Projections, Conjugates, and Decomposing of Complex Numbers.

`complex _FloatN cprojfN (complex _FloatN z)`

  `complex.h` (TS 18661-3:2015): Projections, Conjugates, and Decomposing of Complex Numbers.

`complex _FloatNx cprojfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Projections, Conjugates, and Decomposing of Complex Numbers.

`complex long double cprojl (complex long double z)`

  `complex.h` (ISO): Projections, Conjugates, and Decomposing of Complex Numbers.

`cpu_set_t`

  `sched.h` (GNU): Limiting execution to certain CPUs.

`double creal (complex double z)`

  `complex.h` (ISO): Projections, Conjugates, and Decomposing of Complex Numbers.

`float crealf (complex float z)`

  `complex.h` (ISO): Projections, Conjugates, and Decomposing of Complex Numbers.

`_FloatN crealfN (complex _FloatN z)`

  `complex.h` (TS 18661-3:2015): Projections, Conjugates, and Decomposing of Complex Numbers.

`_FloatNx crealfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Projections, Conjugates, and Decomposing of Complex Numbers.

`long double creall (complex long double z)`

  `complex.h` (ISO): Projections, Conjugates, and Decomposing of Complex Numbers.

`int creat (const char *filename, mode_t mode)`

  `fcntl.h` (POSIX.1): Opening and Closing Files.

`int creat64 (const char *filename, mode_t mode)`

  `fcntl.h` (Unix98): Opening and Closing Files.

`complex double csin (complex double z)`

  `complex.h` (ISO): Trigonometric Functions.

`complex float csinf (complex float z)`

  `complex.h` (ISO): Trigonometric Functions.

`complex _FloatN csinfN (complex _FloatN z)`

  `complex.h` (TS 18661-3:2015): Trigonometric Functions.

`complex _FloatNx csinfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Trigonometric Functions.

`complex double csinh (complex double z)`

  `complex.h` (ISO): Hyperbolic Functions.

`complex float csinhf (complex float z)`

  `complex.h` (ISO): Hyperbolic Functions.

`complex _FloatN csinhfN (complex _FloatN z)`

  `complex.h` (TS 18661-3:2015): Hyperbolic Functions.

`complex _FloatNx csinhfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Hyperbolic Functions.

`complex long double csinhl (complex long double z)`

  `complex.h` (ISO): Hyperbolic Functions.

`complex long double csinl (complex long double z)`

  `complex.h` (ISO): Trigonometric Functions.

`complex double csqrt (complex double z)`

  `complex.h` (ISO): Exponentiation and Logarithms.

`complex float csqrtf (complex float z)`

  `complex.h` (ISO): Exponentiation and Logarithms.

`complex _FloatN csqrtfN (_FloatN z)`

  `complex.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`complex _FloatNx csqrtfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`complex long double csqrtl (complex long double z)`

  `complex.h` (ISO): Exponentiation and Logarithms.

`complex double ctan (complex double z)`

  `complex.h` (ISO): Trigonometric Functions.

`complex float ctanf (complex float z)`

  `complex.h` (ISO): Trigonometric Functions.

`complex _FloatN ctanfN (complex _FloatN z)`

  `complex.h` (TS 18661-3:2015): Trigonometric Functions.

`complex _FloatNx ctanfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Trigonometric Functions.

`complex double ctanh (complex double z)`

  `complex.h` (ISO): Hyperbolic Functions.

`complex float ctanhf (complex float z)`

  `complex.h` (ISO): Hyperbolic Functions.

`complex _FloatN ctanhfN (complex _FloatN z)`

  `complex.h` (TS 18661-3:2015): Hyperbolic Functions.

`complex _FloatNx ctanhfNx (complex _FloatNx z)`

  `complex.h` (TS 18661-3:2015): Hyperbolic Functions.

`complex long double ctanhl (complex long double z)`

  `complex.h` (ISO): Hyperbolic Functions.

`complex long double ctanl (complex long double z)`

  `complex.h` (ISO): Trigonometric Functions.

`char * ctermid (char *string)`

  `stdio.h` (POSIX.1): Identifying the Controlling Terminal.

`char * ctime (const time_t *time)`

  `time.h` (ISO): Formatting Calendar Time.

`char * ctime_r (const time_t *time, char *buffer)`

  `time.h` (???): Formatting Calendar Time.

`char * cuserid (char *string)`

  `stdio.h` (POSIX.1): Identifying Who Logged In.

`double daddl (long double x, long double y)`

  `math.h` (TS 18661-1:2014): Miscellaneous FP arithmetic functions.

`int daylight`

  `time.h` (POSIX.1): State Variables for Time Zones.

`char * dcgettext (const char *domainname, const char *msgid, int category)`

  `libintl.h` (POSIX-1.2024): What has to be done to translate a message?.

`char * dcngettext (const char *domain, const char *msgid1, const char *msgid2, unsigned long int n, int category)`

  `libintl.h` (POSIX-1.2024): Additional functions for more complicated situations.

`double ddivl (long double x, long double y)`

  `math.h` (TS 18661-1:2014): Miscellaneous FP arithmetic functions.

`dev_t`

  `sys/types.h` (POSIX.1): The meaning of the File Attributes.

`double dfmal (long double x, long double y, long double z)`

  `math.h` (TS 18661-1:2014): Miscellaneous FP arithmetic functions.

`char * dgettext (const char *domainname, const char *msgid)`

  `libintl.h` (POSIX-1.2024): What has to be done to translate a message?.

`double difftime (time_t end, time_t begin)`

  `time.h` (ISO): Calculating Elapsed Time.

`struct dirent`

  `dirent.h` (POSIX.1): Format of a Directory Entry.

`int dirfd (DIR *dirstream)`

  `dirent.h` (GNU): Opening a Directory Stream.

`char * dirname (char *path)`

  `libgen.h` (XPG): Finding Tokens in a String.

`div_t div (int numerator, int denominator)`

  `stdlib.h` (ISO): Integer Division.

`div_t`

  `stdlib.h` (ISO): Integer Division.

`struct dl_find_object`

  `dlfcn.h` (GNU): Dynamic Linker Introspection.

`double dmull (long double x, long double y)`

  `math.h` (TS 18661-1:2014): Miscellaneous FP arithmetic functions.

`char * dngettext (const char *domain, const char *msgid1, const char *msgid2, unsigned long int n)`

  `libintl.h` (POSIX-1.2024): Additional functions for more complicated situations.

`int dprintf (int fd, template, ...)`

  `stdio.h` (POSIX): Formatted Output Functions.

`double drand48 (void)`

  `stdlib.h` (SVID): SVID Random Number Function.

`int drand48_r (struct drand48_data *buffer, double *result)`

  `stdlib.h` (GNU): SVID Random Number Function.

`double drem (double numerator, double denominator)`

  `math.h` (BSD): Remainder Functions.

`float dremf (float numerator, float denominator)`

  `math.h` (BSD): Remainder Functions.

`long double dreml (long double numerator, long double denominator)`

  `math.h` (BSD): Remainder Functions.

`double dsqrtl (long double x)`

  `math.h` (TS 18661-1:2014): Miscellaneous FP arithmetic functions.

`double dsubl (long double x, long double y)`

  `math.h` (TS 18661-1:2014): Miscellaneous FP arithmetic functions.

`int dup (int old)`

  `unistd.h` (POSIX.1): Duplicating Descriptors.

`int dup2 (int old, int new)`

  `unistd.h` (POSIX.1): Duplicating Descriptors.

`int dup3 (int old, int new, int flags)`

  `unistd.h` (POSIX.1-2024): Duplicating Descriptors.

`char * ecvt (double value, int ndigit, int *decpt, int *neg)`

  `stdlib.h` (SVID): Old-fashioned System V number-to-string functions.

  `stdlib.h` (Unix98): Old-fashioned System V number-to-string functions.

`int ecvt_r (double value, int ndigit, int *decpt, int *neg, char *buf, size_t len)`

  `stdlib.h` (GNU): Old-fashioned System V number-to-string functions.

`void endfsent (void)`

  `fstab.h` (BSD): The `fstab` file.

`void endgrent (void)`

  `grp.h` (SVID): Scanning the List of All Groups.

  `grp.h` (BSD): Scanning the List of All Groups.

`void endhostent (void)`

  `netdb.h` (BSD): Host Names.

`int endmntent (FILE *stream)`

  `mntent.h` (BSD): The `mtab` file.

`void endnetent (void)`

  `netdb.h` (BSD): Networks Database.

`void endnetgrent (void)`

  `netdb.h` (BSD): Looking up one Netgroup.

`void endprotoent (void)`

  `netdb.h` (BSD): Protocols Database.

`void endpwent (void)`

  `pwd.h` (SVID): Scanning the List of All Users.

  `pwd.h` (BSD): Scanning the List of All Users.

`void endservent (void)`

  `netdb.h` (BSD): The Services Database.

`void endutent (void)`

  `utmp.h` (SVID): Manipulating the User Accounting Database.

`void endutxent (void)`

  `utmpx.h` (XPG4.2): XPG User Accounting Database Functions.

`char ** environ`

  `unistd.h` (POSIX.1): Environment Access.

`error_t envz_add (char **envz, size_t *envz_len, const char *name, const char *value)`

  `envz.h` (GNU): Envz Functions.

`char * envz_entry (const char *envz, size_t envz_len, const char *name)`

  `envz.h` (GNU): Envz Functions.

`char * envz_get (const char *envz, size_t envz_len, const char *name)`

  `envz.h` (GNU): Envz Functions.

`error_t envz_merge (char **envz, size_t *envz_len, const char *envz2, size_t envz2_len, int override)`

  `envz.h` (GNU): Envz Functions.

`void envz_remove (char **envz, size_t *envz_len, const char *name)`

  `envz.h` (GNU): Envz Functions.

`void envz_strip (char **envz, size_t *envz_len)`

  `envz.h` (GNU): Envz Functions.

`double erand48 (unsigned short int xsubi[3])`

  `stdlib.h` (SVID): SVID Random Number Function.

`int erand48_r (unsigned short int xsubi[3], struct drand48_data *buffer, double *result)`

  `stdlib.h` (GNU): SVID Random Number Function.

`double erf (double x)`

  `math.h` (SVID): Special Functions.

`double erfc (double x)`

  `math.h` (SVID): Special Functions.

`float erfcf (float x)`

  `math.h` (SVID): Special Functions.

`_FloatN erfcfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Special Functions.

`_FloatNx erfcfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Special Functions.

`long double erfcl (long double x)`

  `math.h` (SVID): Special Functions.

`float erff (float x)`

  `math.h` (SVID): Special Functions.

`_FloatN erffN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Special Functions.

`_FloatNx erffNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Special Functions.

`long double erfl (long double x)`

  `math.h` (SVID): Special Functions.

`void err (int status, const char *format, …)`

  `err.h` (BSD): Error Messages.

`volatile int errno`

  `errno.h` (ISO): Checking for Errors.

`void error (int status, int errnum, const char *format, …)`

  `error.h` (GNU): Error Messages.

`void error_at_line (int status, int errnum, const char *fname, unsigned int lineno, const char *format, …)`

  `error.h` (GNU): Error Messages.

`unsigned int error_message_count`

  `error.h` (GNU): Error Messages.

`int error_one_per_line`

  `error.h` (GNU): Error Messages.

`void (*error_print_progname) (void)`

  `error.h` (GNU): Error Messages.

`void errx (int status, const char *format, …)`

  `err.h` (BSD): Error Messages.

`int execl (const char *filename, const char *arg0, …)`

  `unistd.h` (POSIX.1): Executing a File.

`int execle (const char *filename, const char *arg0, …, char *const env`[]`)`

  `unistd.h` (POSIX.1): Executing a File.

`int execlp (const char *filename, const char *arg0, …)`

  `unistd.h` (POSIX.1): Executing a File.

`int execv (const char *filename, char *const argv`[]`)`

  `unistd.h` (POSIX.1): Executing a File.

`int execve (const char *filename, char *const argv`[]`, char *const env`[]`)`

  `unistd.h` (POSIX.1): Executing a File.

`int execvp (const char *filename, char *const argv`[]`)`

  `unistd.h` (POSIX.1): Executing a File.

`void exit (int status)`

  `stdlib.h` (ISO): Normal Termination.

`struct exit_status`

  `utmp.h` (SVID): Manipulating the User Accounting Database.

`double exp (double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`double exp10 (double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`float exp10f (float x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`_FloatN exp10fN (_FloatN x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatNx exp10fNx (_FloatNx x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`long double exp10l (long double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`double exp10m1 (double x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`float exp10m1f (float x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatN exp10m1fN (_FloatN x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatNx exp10m1fNx (_FloatNx x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`long double exp10m1l (long double x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`double exp2 (double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`float exp2f (float x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`_FloatN exp2fN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`_FloatNx exp2fNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`long double exp2l (long double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`double exp2m1 (double x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`float exp2m1f (float x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatN exp2m1fN (_FloatN x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatNx exp2m1fNx (_FloatNx x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`long double exp2m1l (long double x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`float expf (float x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`_FloatN expfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`_FloatNx expfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`long double expl (long double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`void explicit_bzero (void *block, size_t len)`

  `string.h` (BSD): Erasing Sensitive Data.

`double expm1 (double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`float expm1f (float x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`_FloatN expm1fN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`_FloatNx expm1fNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`long double expm1l (long double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`_FloatM fMaddfN (_FloatN x, _FloatN y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatM fMaddfNx (_FloatNx x, _FloatNx y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatM fMdivfN (_FloatN x, _FloatN y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatM fMdivfNx (_FloatNx x, _FloatNx y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatM fMfmafN (_FloatN x, _FloatN y, _FloatN z)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatM fMfmafNx (_FloatNx x, _FloatNx y, _FloatNx z)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatM fMmulfN (_FloatN x, _FloatN y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatM fMmulfNx (_FloatNx x, _FloatNx y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatM fMsqrtfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatM fMsqrtfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatM fMsubfN (_FloatN x, _FloatN y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatM fMsubfNx (_FloatNx x, _FloatNx y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatMx fMxaddfN (_FloatN x, _FloatN y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatMx fMxaddfNx (_FloatNx x, _FloatNx y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatMx fMxdivfN (_FloatN x, _FloatN y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatMx fMxdivfNx (_FloatNx x, _FloatNx y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatMx fMxfmafN (_FloatN x, _FloatN y, _FloatN z)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatMx fMxfmafNx (_FloatNx x, _FloatNx y, _FloatNx z)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatMx fMxmulfN (_FloatN x, _FloatN y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatMx fMxmulfNx (_FloatNx x, _FloatNx y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatMx fMxsqrtfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatMx fMxsqrtfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatMx fMxsubfN (_FloatN x, _FloatN y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatMx fMxsubfNx (_FloatNx x, _FloatNx y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`double fabs (double number)`

  `math.h` (ISO): Absolute Value.

`float fabsf (float number)`

  `math.h` (ISO): Absolute Value.

`_FloatN fabsfN (_FloatN number)`

  `math.h` (TS 18661-3:2015): Absolute Value.

`_FloatNx fabsfNx (_FloatNx number)`

  `math.h` (TS 18661-3:2015): Absolute Value.

`long double fabsl (long double number)`

  `math.h` (ISO): Absolute Value.

`int faccessat (int filedes, const char *filename, int how, int flags)`

  `unistd.h` (POSIX.1-2008): Testing Permission to Access a File.

`float fadd (double x, double y)`

  `math.h` (TS 18661-1:2014): Miscellaneous FP arithmetic functions.

`float faddl (long double x, long double y)`

  `math.h` (TS 18661-1:2014): Miscellaneous FP arithmetic functions.

`int fchdir (int filedes)`

  `unistd.h` (XPG): Working Directory.

`int fchmod (int filedes, mode_t mode)`

  `sys/stat.h` (BSD): Assigning File Permissions.

`int fchown (int filedes, uid_t owner, gid_t group)`

  `unistd.h` (BSD): File Owner.

`int fclose (FILE *stream)`

  `stdio.h` (ISO): Closing Streams.

`int fcloseall (void)`

  `stdio.h` (GNU): Closing Streams.

`int fcntl (int filedes, int command, …)`

  `fcntl.h` (POSIX.1): Control Operations on Files.

`char * fcvt (double value, int ndigit, int *decpt, int *neg)`

  `stdlib.h` (SVID): Old-fashioned System V number-to-string functions.

  `stdlib.h` (Unix98): Old-fashioned System V number-to-string functions.

`int fcvt_r (double value, int ndigit, int *decpt, int *neg, char *buf, size_t len)`

  `stdlib.h` (SVID): Old-fashioned System V number-to-string functions.

  `stdlib.h` (Unix98): Old-fashioned System V number-to-string functions.

`fd_set`

  `sys/select.h` (POSIX.1): Waiting for Input or Output.

`int fdatasync (int fildes)`

  `unistd.h` (POSIX): Synchronizing I/O operations.

`double fdim (double x, double y)`

  `math.h` (ISO): Miscellaneous FP arithmetic functions.

`float fdimf (float x, float y)`

  `math.h` (ISO): Miscellaneous FP arithmetic functions.

`_FloatN fdimfN (_FloatN x, _FloatN y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatNx fdimfNx (_FloatNx x, _FloatNx y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`long double fdiml (long double x, long double y)`

  `math.h` (ISO): Miscellaneous FP arithmetic functions.

`float fdiv (double x, double y)`

  `math.h` (TS 18661-1:2014): Miscellaneous FP arithmetic functions.

`float fdivl (long double x, long double y)`

  `math.h` (TS 18661-1:2014): Miscellaneous FP arithmetic functions.

`FILE * fdopen (int filedes, const char *opentype)`

  `stdio.h` (POSIX.1): Descriptors and Streams.

`DIR * fdopendir (int fd)`

  `dirent.h` (GNU): Opening a Directory Stream.

`int feclearexcept (int excepts)`

  `fenv.h` (ISO): Examining the FPU status word.

`int fedisableexcept (int excepts)`

  `fenv.h` (GNU): Floating-Point Control Functions.

`int feenableexcept (int excepts)`

  `fenv.h` (GNU): Floating-Point Control Functions.

`int fegetenv (fenv_t *envp)`

  `fenv.h` (ISO): Floating-Point Control Functions.

`int fegetexcept (void)`

  `fenv.h` (GNU): Floating-Point Control Functions.

`int fegetexceptflag (fexcept_t *flagp, int excepts)`

  `fenv.h` (ISO): Examining the FPU status word.

`int fegetmode (femode_t *modep)`

  `fenv.h` (ISO): Floating-Point Control Functions.

`int fegetround (void)`

  `fenv.h` (ISO): Rounding Modes.

`int feholdexcept (fenv_t *envp)`

  `fenv.h` (ISO): Floating-Point Control Functions.

`int feof (FILE *stream)`

  `stdio.h` (ISO): End-Of-File and Errors.

`int feof_unlocked (FILE *stream)`

  `stdio.h` (GNU): End-Of-File and Errors.

`int feraiseexcept (int excepts)`

  `fenv.h` (ISO): Examining the FPU status word.

`int ferror (FILE *stream)`

  `stdio.h` (ISO): End-Of-File and Errors.

`int ferror_unlocked (FILE *stream)`

  `stdio.h` (GNU): End-Of-File and Errors.

`int fesetenv (const fenv_t *envp)`

  `fenv.h` (ISO): Floating-Point Control Functions.

`int fesetexcept (int excepts)`

  `fenv.h` (ISO): Examining the FPU status word.

`int fesetexceptflag (const fexcept_t *flagp, int excepts)`

  `fenv.h` (ISO): Examining the FPU status word.

`int fesetmode (const femode_t *modep)`

  `fenv.h` (ISO): Floating-Point Control Functions.

`int fesetround (int round)`

  `fenv.h` (ISO): Rounding Modes.

`int fetestexcept (int excepts)`

  `fenv.h` (ISO): Examining the FPU status word.

`int fetestexceptflag (const fexcept_t *flagp, int excepts)`

  `fenv.h` (ISO): Examining the FPU status word.

`int feupdateenv (const fenv_t *envp)`

  `fenv.h` (ISO): Floating-Point Control Functions.

`int fexecve (int fd, char *const argv`[]`, char *const env`[]`)`

  `unistd.h` (POSIX.1): Executing a File.

`int fflush (FILE *stream)`

  `stdio.h` (ISO): Flushing Buffers.

`int fflush_unlocked (FILE *stream)`

  `stdio.h` (POSIX): Flushing Buffers.

`float ffma (double x, double y, double z)`

  `math.h` (TS 18661-1:2014): Miscellaneous FP arithmetic functions.

`float ffmal (long double x, long double y, long double z)`

  `math.h` (TS 18661-1:2014): Miscellaneous FP arithmetic functions.

`int fgetc (FILE *stream)`

  `stdio.h` (ISO): Character Input.

`int fgetc_unlocked (FILE *stream)`

  `stdio.h` (POSIX): Character Input.

`struct group * fgetgrent (FILE *stream)`

  `grp.h` (SVID): Scanning the List of All Groups.

`int fgetgrent_r (FILE *stream, struct group *result_buf, char *buffer, size_t buflen, struct group **result)`

  `grp.h` (GNU): Scanning the List of All Groups.

`int fgetpos (FILE *stream, fpos_t *position)`

  `stdio.h` (ISO): Portable File-Position Functions.

`int fgetpos64 (FILE *stream, fpos64_t *position)`

  `stdio.h` (Unix98): Portable File-Position Functions.

`struct passwd * fgetpwent (FILE *stream)`

  `pwd.h` (SVID): Scanning the List of All Users.

`int fgetpwent_r (FILE *stream, struct passwd *result_buf, char *buffer, size_t buflen, struct passwd **result)`

  `pwd.h` (GNU): Scanning the List of All Users.

`char * fgets (char *s, int count, FILE *stream)`

  `stdio.h` (ISO): Line-Oriented Input.

`char * fgets_unlocked (char *s, int count, FILE *stream)`

  `stdio.h` (GNU): Line-Oriented Input.

`wint_t fgetwc (FILE *stream)`

  `wchar.h` (ISO): Character Input.

`wint_t fgetwc_unlocked (FILE *stream)`

  `wchar.h` (GNU): Character Input.

`wchar_t * fgetws (wchar_t *ws, int count, FILE *stream)`

  `wchar.h` (ISO): Line-Oriented Input.

`wchar_t * fgetws_unlocked (wchar_t *ws, int count, FILE *stream)`

  `wchar.h` (GNU): Line-Oriented Input.

`int fileno (FILE *stream)`

  `stdio.h` (POSIX.1): Descriptors and Streams.

`int fileno_unlocked (FILE *stream)`

  `stdio.h` (GNU): Descriptors and Streams.

`int finite (double x)`

  `math.h` (BSD): Floating-Point Number Classification Functions.

`int finitef (float x)`

  `math.h` (BSD): Floating-Point Number Classification Functions.

`int finitel (long double x)`

  `math.h` (BSD): Floating-Point Number Classification Functions.

`struct flock`

  `fcntl.h` (POSIX.1): File Locks.

`void flockfile (FILE *stream)`

  `stdio.h` (POSIX): Streams and Threads.

`double floor (double x)`

  `math.h` (ISO): Rounding Functions.

`float floorf (float x)`

  `math.h` (ISO): Rounding Functions.

`_FloatN floorfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`_FloatNx floorfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`long double floorl (long double x)`

  `math.h` (ISO): Rounding Functions.

`double fma (double x, double y, double z)`

  `math.h` (ISO): Miscellaneous FP arithmetic functions.

`float fmaf (float x, float y, float z)`

  `math.h` (ISO): Miscellaneous FP arithmetic functions.

`_FloatN fmafN (_FloatN x, _FloatN y, _FloatN z)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatNx fmafNx (_FloatNx x, _FloatNx y, _FloatNx z)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`long double fmal (long double x, long double y, long double z)`

  `math.h` (ISO): Miscellaneous FP arithmetic functions.

`double fmax (double x, double y)`

  `math.h` (ISO): Miscellaneous FP arithmetic functions.

`float fmaxf (float x, float y)`

  `math.h` (ISO): Miscellaneous FP arithmetic functions.

`_FloatN fmaxfN (_FloatN x, _FloatN y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatNx fmaxfNx (_FloatNx x, _FloatNx y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`double fmaximum (double x, double y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`double fmaximum_mag (double x, double y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`double fmaximum_mag_num (double x, double y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`float fmaximum_mag_numf (float x, float y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`_FloatN fmaximum_mag_numfN (_FloatN x, _FloatN y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`_FloatNx fmaximum_mag_numfNx (_FloatNx x, _FloatNx y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`long double fmaximum_mag_numl (long double x, long double y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`float fmaximum_magf (float x, float y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`_FloatN fmaximum_magfN (_FloatN x, _FloatN y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`_FloatNx fmaximum_magfNx (_FloatNx x, _FloatNx y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`long double fmaximum_magl (long double x, long double y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`double fmaximum_num (double x, double y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`float fmaximum_numf (float x, float y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`_FloatN fmaximum_numfN (_FloatN x, _FloatN y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`_FloatNx fmaximum_numfNx (_FloatNx x, _FloatNx y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`long double fmaximum_numl (long double x, long double y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`float fmaximumf (float x, float y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`_FloatN fmaximumfN (_FloatN x, _FloatN y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`_FloatNx fmaximumfNx (_FloatNx x, _FloatNx y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`long double fmaximuml (long double x, long double y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`long double fmaxl (long double x, long double y)`

  `math.h` (ISO): Miscellaneous FP arithmetic functions.

`double fmaxmag (double x, double y)`

  `math.h` (ISO): Miscellaneous FP arithmetic functions.

`float fmaxmagf (float x, float y)`

  `math.h` (ISO): Miscellaneous FP arithmetic functions.

`_FloatN fmaxmagfN (_FloatN x, _FloatN y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatNx fmaxmagfNx (_FloatNx x, _FloatNx y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`long double fmaxmagl (long double x, long double y)`

  `math.h` (ISO): Miscellaneous FP arithmetic functions.

`FILE * fmemopen (void *buf, size_t size, const char *opentype)`

  `stdio.h` (GNU): String Streams.

`double fmin (double x, double y)`

  `math.h` (ISO): Miscellaneous FP arithmetic functions.

`float fminf (float x, float y)`

  `math.h` (ISO): Miscellaneous FP arithmetic functions.

`_FloatN fminfN (_FloatN x, _FloatN y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatNx fminfNx (_FloatNx x, _FloatNx y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`double fminimum (double x, double y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`double fminimum_mag (double x, double y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`double fminimum_mag_num (double x, double y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`float fminimum_mag_numf (float x, float y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`_FloatN fminimum_mag_numfN (_FloatN x, _FloatN y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`_FloatNx fminimum_mag_numfNx (_FloatNx x, _FloatNx y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`long double fminimum_mag_numl (long double x, long double y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`float fminimum_magf (float x, float y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`_FloatN fminimum_magfN (_FloatN x, _FloatN y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`_FloatNx fminimum_magfNx (_FloatNx x, _FloatNx y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`long double fminimum_magl (long double x, long double y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`double fminimum_num (double x, double y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`float fminimum_numf (float x, float y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`_FloatN fminimum_numfN (_FloatN x, _FloatN y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`_FloatNx fminimum_numfNx (_FloatNx x, _FloatNx y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`long double fminimum_numl (long double x, long double y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`float fminimumf (float x, float y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`_FloatN fminimumfN (_FloatN x, _FloatN y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`_FloatNx fminimumfNx (_FloatNx x, _FloatNx y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`long double fminimuml (long double x, long double y)`

  `math.h` (C23): Miscellaneous FP arithmetic functions.

`long double fminl (long double x, long double y)`

  `math.h` (ISO): Miscellaneous FP arithmetic functions.

`double fminmag (double x, double y)`

  `math.h` (ISO): Miscellaneous FP arithmetic functions.

`float fminmagf (float x, float y)`

  `math.h` (ISO): Miscellaneous FP arithmetic functions.

`_FloatN fminmagfN (_FloatN x, _FloatN y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`_FloatNx fminmagfNx (_FloatNx x, _FloatNx y)`

  `math.h` (TS 18661-3:2015): Miscellaneous FP arithmetic functions.

`long double fminmagl (long double x, long double y)`

  `math.h` (ISO): Miscellaneous FP arithmetic functions.

`double fmod (double numerator, double denominator)`

  `math.h` (ISO): Remainder Functions.

`float fmodf (float numerator, float denominator)`

  `math.h` (ISO): Remainder Functions.

`_FloatN fmodfN (_FloatN numerator, _FloatN denominator)`

  `math.h` (TS 18661-3:2015): Remainder Functions.

`_FloatNx fmodfNx (_FloatNx numerator, _FloatNx denominator)`

  `math.h` (TS 18661-3:2015): Remainder Functions.

`long double fmodl (long double numerator, long double denominator)`

  `math.h` (ISO): Remainder Functions.

`int fmtmsg (long int classification, const char *label, int severity, const char *text, const char *action, const char *tag)`

  `fmtmsg.h` (XPG): Printing Formatted Messages.

`float fmul (double x, double y)`

  `math.h` (TS 18661-1:2014): Miscellaneous FP arithmetic functions.

`float fmull (long double x, long double y)`

  `math.h` (TS 18661-1:2014): Miscellaneous FP arithmetic functions.

`int fnmatch (const char *pattern, const char *string, int flags)`

  `fnmatch.h` (POSIX.2): Wildcard Matching.

`FILE * fopen (const char *filename, const char *opentype)`

  `stdio.h` (ISO): Opening Streams.

`FILE * fopen64 (const char *filename, const char *opentype)`

  `stdio.h` (Unix98): Opening Streams.

`FILE * fopencookie (void *cookie, const char *opentype, cookie_io_functions_t io-functions)`

  `stdio.h` (GNU): Custom Streams and Cookies.

`pid_t fork (void)`

  `unistd.h` (POSIX.1): Creating a Process.

`int forkpty (int *amaster, char *name, const struct termios *termp, const struct winsize *winp)`

  `pty.h` (BSD): Opening a Pseudo-Terminal Pair.

`long int fpathconf (int filedes, int parameter)`

  `unistd.h` (POSIX.1): Using `pathconf`.

`int fpclassify (float-type x)`

  `math.h` (ISO): Floating-Point Number Classification Functions.

`fpos64_t`

  `stdio.h` (Unix98): Portable File-Position Functions.

`fpos_t`

  `stdio.h` (ISO): Portable File-Position Functions.

`int fprintf (FILE *stream, const char *template, …)`

  `stdio.h` (ISO): Formatted Output Functions.

`int fputc (int c, FILE *stream)`

  `stdio.h` (ISO): Simple Output by Characters or Lines.

`int fputc_unlocked (int c, FILE *stream)`

  `stdio.h` (POSIX): Simple Output by Characters or Lines.

`int fputs (const char *s, FILE *stream)`

  `stdio.h` (ISO): Simple Output by Characters or Lines.

`int fputs_unlocked (const char *s, FILE *stream)`

  `stdio.h` (GNU): Simple Output by Characters or Lines.

`wint_t fputwc (wchar_t wc, FILE *stream)`

  `wchar.h` (ISO): Simple Output by Characters or Lines.

`wint_t fputwc_unlocked (wchar_t wc, FILE *stream)`

  `wchar.h` (POSIX): Simple Output by Characters or Lines.

`int fputws (const wchar_t *ws, FILE *stream)`

  `wchar.h` (ISO): Simple Output by Characters or Lines.

`int fputws_unlocked (const wchar_t *ws, FILE *stream)`

  `wchar.h` (GNU): Simple Output by Characters or Lines.

`size_t fread (void *data, size_t size, size_t count, FILE *stream)`

  `stdio.h` (ISO): Block Input/Output.

`size_t fread_unlocked (void *data, size_t size, size_t count, FILE *stream)`

  `stdio.h` (GNU): Block Input/Output.

`void free (void *ptr)`

  `malloc.h` (ISO): Freeing Memory Allocated with `malloc`.

  `stdlib.h` (ISO): Freeing Memory Allocated with `malloc`.

`void free_aligned_sized (void *ptr, size_t alignment, size_t size)`

  `stdlib.h` (ISO): Freeing Memory Allocated with `malloc`.

`void free_sized (void *ptr, size_t size)`

  `stdlib.h` (ISO): Freeing Memory Allocated with `malloc`.

`FILE * freopen (const char *filename, const char *opentype, FILE *stream)`

  `stdio.h` (ISO): Opening Streams.

`FILE * freopen64 (const char *filename, const char *opentype, FILE *stream)`

  `stdio.h` (Unix98): Opening Streams.

`double frexp (double value, int *exponent)`

  `math.h` (ISO): Normalization Functions.

`float frexpf (float value, int *exponent)`

  `math.h` (ISO): Normalization Functions.

`_FloatN frexpfN (_FloatN value, int *exponent)`

  `math.h` (TS 18661-3:2015): Normalization Functions.

`_FloatNx frexpfNx (_FloatNx value, int *exponent)`

  `math.h` (TS 18661-3:2015): Normalization Functions.

`long double frexpl (long double value, int *exponent)`

  `math.h` (ISO): Normalization Functions.

`double fromfp (double x, int round, unsigned int width)`

  `math.h` (ISO): Rounding Functions.

`float fromfpf (float x, int round, unsigned int width)`

  `math.h` (ISO): Rounding Functions.

`_FloatN fromfpfN (_FloatN x, int round, unsigned int width)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`_FloatNx fromfpfNx (_FloatNx x, int round, unsigned int width)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`long double fromfpl (long double x, int round, unsigned int width)`

  `math.h` (ISO): Rounding Functions.

`double fromfpx (double x, int round, unsigned int width)`

  `math.h` (ISO): Rounding Functions.

`float fromfpxf (float x, int round, unsigned int width)`

  `math.h` (ISO): Rounding Functions.

`_FloatN fromfpxfN (_FloatN x, int round, unsigned int width)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`_FloatNx fromfpxfNx (_FloatNx x, int round, unsigned int width)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`long double fromfpxl (long double x, int round, unsigned int width)`

  `math.h` (ISO): Rounding Functions.

`int fscanf (FILE *stream, const char *template, …)`

  `stdio.h` (ISO): Formatted Input Functions.

`int fseek (FILE *stream, long int offset, int whence)`

  `stdio.h` (ISO): File Positioning.

`int fseeko (FILE *stream, off_t offset, int whence)`

  `stdio.h` (Unix98): File Positioning.

`int fseeko64 (FILE *stream, off64_t offset, int whence)`

  `stdio.h` (Unix98): File Positioning.

`int fsetpos (FILE *stream, const fpos_t *position)`

  `stdio.h` (ISO): Portable File-Position Functions.

`int fsetpos64 (FILE *stream, const fpos64_t *position)`

  `stdio.h` (Unix98): Portable File-Position Functions.

`float fsqrt (double x)`

  `math.h` (TS 18661-1:2014): Miscellaneous FP arithmetic functions.

`float fsqrtl (long double x)`

  `math.h` (TS 18661-1:2014): Miscellaneous FP arithmetic functions.

`struct fstab`

  `fstab.h` (BSD): The `fstab` file.

`int fstat (int filedes, struct stat *buf)`

  `sys/stat.h` (POSIX.1): Reading the Attributes of a File.

`int fstat64 (int filedes, struct stat64 *buf)`

  `sys/stat.h` (Unix98): Reading the Attributes of a File.

`int fstatat (int filedes, const char *filename, struct stat *buf, int flags)`

  `sys/stat.h` (POSIX.1): Reading the Attributes of a File.

`int fstatat64 (int filedes, const char *filename, struct stat64 *buf, int flags)`

  `sys/stat.h` (GNU): Reading the Attributes of a File.

`float fsub (double x, double y)`

  `math.h` (TS 18661-1:2014): Miscellaneous FP arithmetic functions.

`float fsubl (long double x, long double y)`

  `math.h` (TS 18661-1:2014): Miscellaneous FP arithmetic functions.

`int fsync (int fildes)`

  `unistd.h` (POSIX): Synchronizing I/O operations.

`long int ftell (FILE *stream)`

  `stdio.h` (ISO): File Positioning.

`off_t ftello (FILE *stream)`

  `stdio.h` (Unix98): File Positioning.

`off64_t ftello64 (FILE *stream)`

  `stdio.h` (Unix98): File Positioning.

`int ftruncate (int fd, off_t length)`

  `unistd.h` (POSIX): File Size.

`int ftruncate64 (int id, off64_t length)`

  `unistd.h` (Unix98): File Size.

`int ftrylockfile (FILE *stream)`

  `stdio.h` (POSIX): Streams and Threads.

`int ftw (const char *filename, __ftw_func_t func, int descriptors)`

  `ftw.h` (SVID): Working with Directory Trees.

`int ftw64 (const char *filename, __ftw64_func_t func, int descriptors)`

  `ftw.h` (Unix98): Working with Directory Trees.

`void funlockfile (FILE *stream)`

  `stdio.h` (POSIX): Streams and Threads.

`int futimens (int filedes, const struct timespec tsp`[2]`)`

  `sys/stat.h` (POSIX.1-2008): File Times.

`int futimes (int fd, const struct timeval tvp`[2]`)`

  `sys/time.h` (BSD): File Times.

`int fwide (FILE *stream, int mode)`

  `wchar.h` (ISO): Streams in Internationalized Applications.

`int fwprintf (FILE *stream, const wchar_t *template, …)`

  `wchar.h` (ISO): Formatted Output Functions.

`size_t fwrite (const void *data, size_t size, size_t count, FILE *stream)`

  `stdio.h` (ISO): Block Input/Output.

`size_t fwrite_unlocked (const void *data, size_t size, size_t count, FILE *stream)`

  `stdio.h` (GNU): Block Input/Output.

`int fwscanf (FILE *stream, const wchar_t *template, …)`

  `wchar.h` (ISO): Formatted Input Functions.

`double gamma (double x)`

  `math.h` (SVID): Special Functions.

`float gammaf (float x)`

  `math.h` (SVID): Special Functions.

`long double gammal (long double x)`

  `math.h` (SVID): Special Functions.

`char * gcvt (double value, int ndigit, char *buf)`

  `stdlib.h` (SVID): Old-fashioned System V number-to-string functions.

  `stdlib.h` (Unix98): Old-fashioned System V number-to-string functions.

`long int get_avphys_pages (void)`

  `sys/sysinfo.h` (GNU): How to get information about the memory subsystem?.

`char * get_current_dir_name (void)`

  `unistd.h` (GNU): Working Directory.

`int get_nprocs (void)`

  `sys/sysinfo.h` (GNU): Learn about the processors available.

`int get_nprocs_conf (void)`

  `sys/sysinfo.h` (GNU): Learn about the processors available.

`long int get_phys_pages (void)`

  `sys/sysinfo.h` (GNU): How to get information about the memory subsystem?.

`unsigned long int getauxval (unsigned long int type)`

  `sys/auxv.h` (???): Auxiliary Vector.

`int getc (FILE *stream)`

  `stdio.h` (ISO): Character Input.

`int getc_unlocked (FILE *stream)`

  `stdio.h` (POSIX): Character Input.

`int getchar (void)`

  `stdio.h` (ISO): Character Input.

`int getchar_unlocked (void)`

  `stdio.h` (POSIX): Character Input.

`int getcontext (ucontext_t *ucp)`

  `ucontext.h` (SVID): Complete Context Control.

`int getcpu (unsigned int *cpu, unsigned int *node)`

  `<sched.h>` (Linux): Limiting execution to certain CPUs.

`char * getcwd (char *buffer, size_t size)`

  `unistd.h` (POSIX.1): Working Directory.

`struct tm * getdate (const char *string)`

  `time.h` (Unix98): A More User-friendly Way to Parse Times and Dates.

`getdate_err`

  `time.h` (Unix98): A More User-friendly Way to Parse Times and Dates.

`int getdate_r (const char *string, struct tm *tp)`

  `time.h` (GNU): A More User-friendly Way to Parse Times and Dates.

`ssize_t getdelim (char **restrict lineptr, size_t *restrict n, int delimiter, FILE *restrict stream)`

  `stdio.h` (POSIX.1-2008): Line-Oriented Input.

`ssize_t getdents64 (int fd, void *buffer, size_t length)`

  `dirent.h` (Linux): Low-level Directory Access.

`int getdomainname (char *name, size_t length)`

  `unistd.h` (???): Host Identification.

`gid_t getegid (void)`

  `unistd.h` (POSIX.1): Reading the Persona of a Process.

`int getentropy (void *buffer, size_t length)`

  `sys/random.h` (GNU): Generating Unpredictable Bytes.

`char * getenv (const char *name)`

  `stdlib.h` (ISO): Environment Access.

`uid_t geteuid (void)`

  `unistd.h` (POSIX.1): Reading the Persona of a Process.

`struct fstab * getfsent (void)`

  `fstab.h` (BSD): The `fstab` file.

`struct fstab * getfsfile (const char *name)`

  `fstab.h` (BSD): The `fstab` file.

`struct fstab * getfsspec (const char *name)`

  `fstab.h` (BSD): The `fstab` file.

`gid_t getgid (void)`

  `unistd.h` (POSIX.1): Reading the Persona of a Process.

`struct group * getgrent (void)`

  `grp.h` (SVID): Scanning the List of All Groups.

  `grp.h` (BSD): Scanning the List of All Groups.

`int getgrent_r (struct group *result_buf, char *buffer, size_t buflen, struct group **result)`

  `grp.h` (GNU): Scanning the List of All Groups.

`struct group * getgrgid (gid_t gid)`

  `grp.h` (POSIX.1): Looking Up One Group.

`int getgrgid_r (gid_t gid, struct group *result_buf, char *buffer, size_t buflen, struct group **result)`

  `grp.h` (POSIX.1c): Looking Up One Group.

`struct group * getgrnam (const char *name)`

  `grp.h` (SVID): Looking Up One Group.

  `grp.h` (BSD): Looking Up One Group.

`int getgrnam_r (const char *name, struct group *result_buf, char *buffer, size_t buflen, struct group **result)`

  `grp.h` (POSIX.1c): Looking Up One Group.

`int getgrouplist (const char *user, gid_t group, gid_t *groups, int *ngroups)`

  `grp.h` (BSD): Setting the Group IDs.

`int getgroups (int count, gid_t *groups)`

  `unistd.h` (POSIX.1): Reading the Persona of a Process.

`struct hostent * gethostbyaddr (const void *addr, socklen_t length, int format)`

  `netdb.h` (BSD): Host Names.

`int gethostbyaddr_r (const void *addr, socklen_t length, int format, struct hostent *restrict result_buf, char *restrict buf, size_t buflen, struct hostent **restrict result, int *restrict h_errnop)`

  `netdb.h` (GNU): Host Names.

`struct hostent * gethostbyname (const char *name)`

  `netdb.h` (BSD): Host Names.

`struct hostent * gethostbyname2 (const char *name, int af)`

  `netdb.h` (IPv6 Basic API): Host Names.

`int gethostbyname2_r (const char *name, int af, struct hostent *restrict result_buf, char *restrict buf, size_t buflen, struct hostent **restrict result, int *restrict h_errnop)`

  `netdb.h` (GNU): Host Names.

`int gethostbyname_r (const char *restrict name, struct hostent *restrict result_buf, char *restrict buf, size_t buflen, struct hostent **restrict result, int *restrict h_errnop)`

  `netdb.h` (GNU): Host Names.

`struct hostent * gethostent (void)`

  `netdb.h` (BSD): Host Names.

`long int gethostid (void)`

  `unistd.h` (BSD): Host Identification.

`int gethostname (char *name, size_t size)`

  `unistd.h` (BSD): Host Identification.

`int getitimer (int which, struct itimerval *old)`

  `sys/time.h` (BSD): Setting an Alarm.

`ssize_t getline (char **restrict lineptr, size_t *restrict n, FILE *restrict stream)`

  `stdio.h` (POSIX.1-2008): Line-Oriented Input.

`int getloadavg (double loadavg[], int nelem)`

  `stdlib.h` (BSD): Learn about the processors available.

`char * getlogin (void)`

  `unistd.h` (POSIX.1): Identifying Who Logged In.

`struct mntent * getmntent (FILE *stream)`

  `mntent.h` (BSD): The `mtab` file.

`struct mntent * getmntent_r (FILE *stream, struct mntent *result, char *buffer, int bufsize)`

  `mntent.h` (BSD): The `mtab` file.

`struct netent * getnetbyaddr (uint32_t net, int type)`

  `netdb.h` (BSD): Networks Database.

`struct netent * getnetbyname (const char *name)`

  `netdb.h` (BSD): Networks Database.

`struct netent * getnetent (void)`

  `netdb.h` (BSD): Networks Database.

`int getnetgrent (char **hostp, char **userp, char **domainp)`

  `netdb.h` (BSD): Looking up one Netgroup.

`int getnetgrent_r (char **hostp, char **userp, char **domainp, char *buffer, size_t buflen)`

  `netdb.h` (GNU): Looking up one Netgroup.

`int getopt (int argc, char *const *argv, const char *options)`

  `unistd.h` (POSIX.2): Using the `getopt` function.

`int getopt_long (int argc, char *const *argv, const char *shortopts, const struct option *longopts, int *indexptr)`

  `getopt.h` (GNU): Parsing Long Options with `getopt_long`.

`int getopt_long_only (int argc, char *const *argv, const char *shortopts, const struct option *longopts, int *indexptr)`

  `getopt.h` (GNU): Parsing Long Options with `getopt_long`.

`int getpagesize (void)`

  `unistd.h` (BSD): How to get information about the memory subsystem?.

`char * getpass (const char *prompt)`

  `unistd.h` (BSD): Reading Passphrases.

`double getpayload (const double *x)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`float getpayloadf (const float *x)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`_FloatN getpayloadfN (const _FloatN *x)`

  `math.h` (TS 18661-3:2015): Setting and modifying single bits of FP values.

`_FloatNx getpayloadfNx (const _FloatNx *x)`

  `math.h` (TS 18661-3:2015): Setting and modifying single bits of FP values.

`long double getpayloadl (const long double *x)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`int getpeername (int socket, struct sockaddr *addr, socklen_t *length-ptr)`

  `sys/socket.h` (BSD): Who is Connected to Me?.

`int getpgid (pid_t pid)`

  `unistd.h` (POSIX.1): Process Group Functions.

`pid_t getpgrp (void)`

  `unistd.h` (POSIX.1): Process Group Functions.

`pid_t getpid (void)`

  `unistd.h` (POSIX.1): Process Identification.

`pid_t getppid (void)`

  `unistd.h` (POSIX.1): Process Identification.

`int getpriority (int class, int id)`

  `sys/resource.h` (BSD): Functions For Traditional Scheduling.

  `sys/resource.h` (POSIX): Functions For Traditional Scheduling.

`struct protoent * getprotobyname (const char *name)`

  `netdb.h` (BSD): Protocols Database.

`struct protoent * getprotobynumber (int protocol)`

  `netdb.h` (BSD): Protocols Database.

`struct protoent * getprotoent (void)`

  `netdb.h` (BSD): Protocols Database.

`int getpt (void)`

  `stdlib.h` (GNU): Allocating Pseudo-Terminals.

`struct passwd * getpwent (void)`

  `pwd.h` (POSIX.1): Scanning the List of All Users.

`int getpwent_r (struct passwd *result_buf, char *buffer, size_t buflen, struct passwd **result)`

  `pwd.h` (GNU): Scanning the List of All Users.

`struct passwd * getpwnam (const char *name)`

  `pwd.h` (POSIX.1): Looking Up One User.

`int getpwnam_r (const char *name, struct passwd *result_buf, char *buffer, size_t buflen, struct passwd **result)`

  `pwd.h` (POSIX.1c): Looking Up One User.

`struct passwd * getpwuid (uid_t uid)`

  `pwd.h` (POSIX.1): Looking Up One User.

`int getpwuid_r (uid_t uid, struct passwd *result_buf, char *buffer, size_t buflen, struct passwd **result)`

  `pwd.h` (POSIX.1c): Looking Up One User.

`ssize_t getrandom (void *buffer, size_t length, unsigned int flags)`

  `sys/random.h` (GNU): Generating Unpredictable Bytes.

`int getrlimit (int resource, struct rlimit *rlp)`

  `sys/resource.h` (BSD): Limiting Resource Usage.

`int getrlimit64 (int resource, struct rlimit64 *rlp)`

  `sys/resource.h` (Unix98): Limiting Resource Usage.

`int getrusage (int processes, struct rusage *rusage)`

  `sys/resource.h` (BSD): Resource Usage.

`char * gets (char *s)`

  `stdio.h` (ISO): Line-Oriented Input.

`struct servent * getservbyname (const char *name, const char *proto)`

  `netdb.h` (BSD): The Services Database.

`struct servent * getservbyport (int port, const char *proto)`

  `netdb.h` (BSD): The Services Database.

`struct servent * getservent (void)`

  `netdb.h` (BSD): The Services Database.

`pid_t getsid (pid_t pid)`

  `unistd.h` (SVID): Process Group Functions.

`int getsockname (int socket, struct sockaddr *addr, socklen_t *length-ptr)`

  `sys/socket.h` (BSD): Reading the Address of a Socket.

`int getsockopt (int socket, int level, int optname, void *optval, socklen_t *optlen-ptr)`

  `sys/socket.h` (BSD): Socket Option Functions.

`int getsubopt (char **restrict optionp, char *const *restrict tokens, char **restrict valuep)`

  `stdlib.h` (POSIX): Parsing of Suboptions.

`char * gettext (const char *msgid)`

  `libintl.h` (POSIX-1.2024): What has to be done to translate a message?.

`pid_t gettid (void)`

  `unistd.h` (Linux): Process Identification.

`int gettimeofday (struct timeval *tp, void *tzp)`

  `sys/time.h` (BSD): Getting the Time.

`uid_t getuid (void)`

  `unistd.h` (POSIX.1): Reading the Persona of a Process.

`mode_t getumask (void)`

  `sys/stat.h` (GNU): Assigning File Permissions.

`struct utmp * getutent (void)`

  `utmp.h` (SVID): Manipulating the User Accounting Database.

`int getutent_r (struct utmp *buffer, struct utmp **result)`

  `utmp.h` (GNU): Manipulating the User Accounting Database.

`struct utmp * getutid (const struct utmp *id)`

  `utmp.h` (SVID): Manipulating the User Accounting Database.

`int getutid_r (const struct utmp *id, struct utmp *buffer, struct utmp **result)`

  `utmp.h` (GNU): Manipulating the User Accounting Database.

`struct utmp * getutline (const struct utmp *line)`

  `utmp.h` (SVID): Manipulating the User Accounting Database.

`int getutline_r (const struct utmp *line, struct utmp *buffer, struct utmp **result)`

  `utmp.h` (GNU): Manipulating the User Accounting Database.

`int getutmp (const struct utmpx *utmpx, struct utmp *utmp)`

  `utmp.h` (GNU): XPG User Accounting Database Functions.

  `utmpx.h` (GNU): XPG User Accounting Database Functions.

`int getutmpx (const struct utmp *utmp, struct utmpx *utmpx)`

  `utmp.h` (GNU): XPG User Accounting Database Functions.

  `utmpx.h` (GNU): XPG User Accounting Database Functions.

`struct utmpx * getutxent (void)`

  `utmpx.h` (XPG4.2): XPG User Accounting Database Functions.

`struct utmpx * getutxid (const struct utmpx *id)`

  `utmpx.h` (XPG4.2): XPG User Accounting Database Functions.

`struct utmpx * getutxline (const struct utmpx *line)`

  `utmpx.h` (XPG4.2): XPG User Accounting Database Functions.

`int getw (FILE *stream)`

  `stdio.h` (SVID): Character Input.

`wint_t getwc (FILE *stream)`

  `wchar.h` (ISO): Character Input.

`wint_t getwc_unlocked (FILE *stream)`

  `wchar.h` (GNU): Character Input.

`wint_t getwchar (void)`

  `wchar.h` (ISO): Character Input.

`wint_t getwchar_unlocked (void)`

  `wchar.h` (GNU): Character Input.

`char * getwd (char *buffer)`

  `unistd.h` (BSD): Working Directory.

`gid_t`

  `sys/types.h` (POSIX.1): Reading the Persona of a Process.

`int glob (const char *pattern, int flags, int (*errfunc) (const char *filename, int error-code), glob_t *vector-ptr)`

  `glob.h` (POSIX.2): Calling `glob`.

`int glob64 (const char *pattern, int flags, int (*errfunc) (const char *filename, int error-code), glob64_t *vector-ptr)`

  `glob.h` (GNU): Calling `glob`.

`glob64_t`

  `glob.h` (GNU): Calling `glob`.

`glob_t`

  `glob.h` (POSIX.2): Calling `glob`.

`void globfree (glob_t *pglob)`

  `glob.h` (POSIX.2): More Flags for Globbing.

`void globfree64 (glob64_t *pglob)`

  `glob.h` (GNU): More Flags for Globbing.

`struct tm * gmtime (const time_t *time)`

  `time.h` (ISO): Broken-down Time.

`struct tm * gmtime_r (const time_t *time, struct tm *resultp)`

  `time.h` (POSIX.1c): Broken-down Time.

`int grantpt (int filedes)`

  `stdlib.h` (SVID): Allocating Pseudo-Terminals.

  `stdlib.h` (XPG4.2): Allocating Pseudo-Terminals.

`struct group`

  `grp.h` (POSIX.1): The Data Structure for a Group.

`int gsignal (int signum)`

  `signal.h` (SVID): Signaling Yourself.

`int gtty (int filedes, struct sgttyb *attributes)`

  `sgtty.h` (BSD): BSD Terminal Modes.

`char * hasmntopt (const struct mntent *mnt, const char *opt)`

  `mntent.h` (BSD): The `mtab` file.

`int hcreate (size_t nel)`

  `search.h` (SVID): The `hsearch` function..

`int hcreate_r (size_t nel, struct hsearch_data *htab)`

  `search.h` (GNU): The `hsearch` function..

`void hdestroy (void)`

  `search.h` (SVID): The `hsearch` function..

`void hdestroy_r (struct hsearch_data *htab)`

  `search.h` (GNU): The `hsearch` function..

`struct hostent`

  `netdb.h` (BSD): Host Names.

`ENTRY * hsearch (ENTRY item, ACTION action)`

  `search.h` (SVID): The `hsearch` function..

`int hsearch_r (ENTRY item, ACTION action, ENTRY **retval, struct hsearch_data *htab)`

  `search.h` (GNU): The `hsearch` function..

`uint32_t htonl (uint32_t hostlong)`

  `netinet/in.h` (BSD): Byte Order Conversion.

`uint16_t htons (uint16_t hostshort)`

  `netinet/in.h` (BSD): Byte Order Conversion.

`double hypot (double x, double y)`

  `math.h` (ISO): Exponentiation and Logarithms.

`float hypotf (float x, float y)`

  `math.h` (ISO): Exponentiation and Logarithms.

`_FloatN hypotfN (_FloatN x, _FloatN y)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`_FloatNx hypotfNx (_FloatNx x, _FloatNx y)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`long double hypotl (long double x, long double y)`

  `math.h` (ISO): Exponentiation and Logarithms.

`size_t iconv (iconv_t cd, char **inbuf, size_t *inbytesleft, char **outbuf, size_t *outbytesleft)`

  `iconv.h` (XPG2): Generic Character Set Conversion Interface.

`int iconv_close (iconv_t cd)`

  `iconv.h` (XPG2): Generic Character Set Conversion Interface.

`iconv_t iconv_open (const char *tocode, const char *fromcode)`

  `iconv.h` (XPG2): Generic Character Set Conversion Interface.

`iconv_t`

  `iconv.h` (XPG2): Generic Character Set Conversion Interface.

`void if_freenameindex (struct if_nameindex *ptr)`

  `net/if.h` (IPv6 basic API): Interface Naming.

`char * if_indextoname (unsigned int ifindex, char *ifname)`

  `net/if.h` (IPv6 basic API): Interface Naming.

`struct if_nameindex`

  `net/if.h` (IPv6 basic API): Interface Naming.

`struct if_nameindex * if_nameindex (void)`

  `net/if.h` (IPv6 basic API): Interface Naming.

`unsigned int if_nametoindex (const char *ifname)`

  `net/if.h` (IPv6 basic API): Interface Naming.

`int ilogb (double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`int ilogbf (float x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`int ilogbfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`int ilogbfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`int ilogbl (long double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`intmax_t imaxabs (intmax_t number)`

  `inttypes.h` (ISO): Absolute Value.

`imaxdiv_t imaxdiv (intmax_t numerator, intmax_t denominator)`

  `inttypes.h` (ISO): Integer Division.

`imaxdiv_t`

  `inttypes.h` (ISO): Integer Division.

`struct in6_addr`

  `netinet/in.h` (IPv6 basic API): Host Address Data Type.

`struct in6_addr in6addr_any`

  `netinet/in.h` (IPv6 basic API): Host Address Data Type.

`struct in6_addr in6addr_loopback`

  `netinet/in.h` (IPv6 basic API): Host Address Data Type.

`struct in_addr`

  `netinet/in.h` (BSD): Host Address Data Type.

`char * index (const char *string, int c)`

  `string.h` (BSD): Search Functions.

`uint32_t inet_addr (const char *name)`

  `arpa/inet.h` (BSD): Host Address Functions.

`int inet_aton (const char *name, struct in_addr *addr)`

  `arpa/inet.h` (BSD): Host Address Functions.

`uint32_t inet_lnaof (struct in_addr addr)`

  `arpa/inet.h` (BSD): Host Address Functions.

`struct in_addr inet_makeaddr (uint32_t net, uint32_t local)`

  `arpa/inet.h` (BSD): Host Address Functions.

`uint32_t inet_netof (struct in_addr addr)`

  `arpa/inet.h` (BSD): Host Address Functions.

`uint32_t inet_network (const char *name)`

  `arpa/inet.h` (BSD): Host Address Functions.

`char * inet_ntoa (struct in_addr addr)`

  `arpa/inet.h` (BSD): Host Address Functions.

`const char * inet_ntop (int af, const void *cp, char *buf, socklen_t len)`

  `arpa/inet.h` (IPv6 basic API): Host Address Functions.

`int inet_pton (int af, const char *cp, void *buf)`

  `arpa/inet.h` (IPv6 basic API): Host Address Functions.

`int initgroups (const char *user, gid_t group)`

  `grp.h` (BSD): Setting the Group IDs.

`char * initstate (unsigned int seed, char *state, size_t size)`

  `stdlib.h` (BSD): BSD Random Number Functions.

`int initstate_r (unsigned int seed, char *restrict statebuf, size_t statelen, struct random_data *restrict buf)`

  `stdlib.h` (GNU): BSD Random Number Functions.

`int innetgr (const char *netgroup, const char *host, const char *user, const char *domain)`

  `netdb.h` (BSD): Testing for Netgroup Membership.

`ino64_t`

  `sys/types.h` (Unix98): The meaning of the File Attributes.

`ino_t`

  `sys/types.h` (POSIX.1): The meaning of the File Attributes.

`int ioctl (int filedes, int command, …)`

  `sys/ioctl.h` (BSD): Generic I/O Control operations.

`struct iovec`

  `sys/uio.h` (BSD): Fast Scatter-Gather I/O.

`int isalnum (int c)`

  `ctype.h` (ISO): Classification of Characters.

`int isalpha (int c)`

  `ctype.h` (ISO): Classification of Characters.

`int isascii (int c)`

  `ctype.h` (SVID): Classification of Characters.

  `ctype.h` (BSD): Classification of Characters.

`int isatty (int filedes)`

  `unistd.h` (POSIX.1): Identifying Terminals.

`int isblank (int c)`

  `ctype.h` (ISO): Classification of Characters.

`int iscanonical (float-type x)`

  `math.h` (ISO): Floating-Point Number Classification Functions.

`int iscntrl (int c)`

  `ctype.h` (ISO): Classification of Characters.

`int isdigit (int c)`

  `ctype.h` (ISO): Classification of Characters.

`int iseqsig (real-floating x, real-floating y)`

  `math.h` (ISO): Floating-Point Comparison Functions.

`int isfinite (float-type x)`

  `math.h` (ISO): Floating-Point Number Classification Functions.

`int isgraph (int c)`

  `ctype.h` (ISO): Classification of Characters.

`int isgreater (real-floating x, real-floating y)`

  `math.h` (ISO): Floating-Point Comparison Functions.

`int isgreaterequal (real-floating x, real-floating y)`

  `math.h` (ISO): Floating-Point Comparison Functions.

`int isinf (double x)`

  `math.h` (BSD): Floating-Point Number Classification Functions.

`int isinff (float x)`

  `math.h` (BSD): Floating-Point Number Classification Functions.

`int isinfl (long double x)`

  `math.h` (BSD): Floating-Point Number Classification Functions.

`int isless (real-floating x, real-floating y)`

  `math.h` (ISO): Floating-Point Comparison Functions.

`int islessequal (real-floating x, real-floating y)`

  `math.h` (ISO): Floating-Point Comparison Functions.

`int islessgreater (real-floating x, real-floating y)`

  `math.h` (ISO): Floating-Point Comparison Functions.

`int islower (int c)`

  `ctype.h` (ISO): Classification of Characters.

`int isnan (float-type x)`

  `math.h` (ISO): Floating-Point Number Classification Functions.

`int isnan (double x)`

  `math.h` (BSD): Floating-Point Number Classification Functions.

`int isnanf (float x)`

  `math.h` (BSD): Floating-Point Number Classification Functions.

`int isnanl (long double x)`

  `math.h` (BSD): Floating-Point Number Classification Functions.

`int isnormal (float-type x)`

  `math.h` (ISO): Floating-Point Number Classification Functions.

`int isprint (int c)`

  `ctype.h` (ISO): Classification of Characters.

`int ispunct (int c)`

  `ctype.h` (ISO): Classification of Characters.

`int issignaling (float-type x)`

  `math.h` (ISO): Floating-Point Number Classification Functions.

`int isspace (int c)`

  `ctype.h` (ISO): Classification of Characters.

`int issubnormal (float-type x)`

  `math.h` (ISO): Floating-Point Number Classification Functions.

`int isunordered (real-floating x, real-floating y)`

  `math.h` (ISO): Floating-Point Comparison Functions.

`int isupper (int c)`

  `ctype.h` (ISO): Classification of Characters.

`int iswalnum (wint_t wc)`

  `wctype.h` (ISO): Character class determination for wide characters.

`int iswalpha (wint_t wc)`

  `wctype.h` (ISO): Character class determination for wide characters.

`int iswblank (wint_t wc)`

  `wctype.h` (ISO): Character class determination for wide characters.

`int iswcntrl (wint_t wc)`

  `wctype.h` (ISO): Character class determination for wide characters.

`int iswctype (wint_t wc, wctype_t desc)`

  `wctype.h` (ISO): Character class determination for wide characters.

`int iswdigit (wint_t wc)`

  `wctype.h` (ISO): Character class determination for wide characters.

`int iswgraph (wint_t wc)`

  `wctype.h` (ISO): Character class determination for wide characters.

`int iswlower (wint_t wc)`

  `ctype.h` (ISO): Character class determination for wide characters.

`int iswprint (wint_t wc)`

  `wctype.h` (ISO): Character class determination for wide characters.

`int iswpunct (wint_t wc)`

  `wctype.h` (ISO): Character class determination for wide characters.

`int iswspace (wint_t wc)`

  `wctype.h` (ISO): Character class determination for wide characters.

`int iswupper (wint_t wc)`

  `wctype.h` (ISO): Character class determination for wide characters.

`int iswxdigit (wint_t wc)`

  `wctype.h` (ISO): Character class determination for wide characters.

`int isxdigit (int c)`

  `ctype.h` (ISO): Classification of Characters.

`int iszero (float-type x)`

  `math.h` (ISO): Floating-Point Number Classification Functions.

`struct itimerval`

  `sys/time.h` (BSD): Setting an Alarm.

`double j0 (double x)`

  `math.h` (SVID): Special Functions.

`float j0f (float x)`

  `math.h` (SVID): Special Functions.

`_FloatN j0fN (_FloatN x)`

  `math.h` (GNU): Special Functions.

`_FloatNx j0fNx (_FloatNx x)`

  `math.h` (GNU): Special Functions.

`long double j0l (long double x)`

  `math.h` (SVID): Special Functions.

`double j1 (double x)`

  `math.h` (SVID): Special Functions.

`float j1f (float x)`

  `math.h` (SVID): Special Functions.

`_FloatN j1fN (_FloatN x)`

  `math.h` (GNU): Special Functions.

`_FloatNx j1fNx (_FloatNx x)`

  `math.h` (GNU): Special Functions.

`long double j1l (long double x)`

  `math.h` (SVID): Special Functions.

`jmp_buf`

  `setjmp.h` (ISO): Details of Non-Local Exits.

`double jn (int n, double x)`

  `math.h` (SVID): Special Functions.

`float jnf (int n, float x)`

  `math.h` (SVID): Special Functions.

`_FloatN jnfN (int n, _FloatN x)`

  `math.h` (GNU): Special Functions.

`_FloatNx jnfNx (int n, _FloatNx x)`

  `math.h` (GNU): Special Functions.

`long double jnl (int n, long double x)`

  `math.h` (SVID): Special Functions.

`long int jrand48 (unsigned short int xsubi[3])`

  `stdlib.h` (SVID): SVID Random Number Function.

`int jrand48_r (unsigned short int xsubi[3], struct drand48_data *buffer, long int *result)`

  `stdlib.h` (GNU): SVID Random Number Function.

`int kill (pid_t pid, int signum)`

  `signal.h` (POSIX.1): Signaling Another Process.

`int killpg (int pgid, int signum)`

  `signal.h` (BSD): Signaling Another Process.

`char * l64a (long int n)`

  `stdlib.h` (XPG): Encode Binary Data.

`long int labs (long int number)`

  `stdlib.h` (ISO): Absolute Value.

`void lcong48 (unsigned short int param[7])`

  `stdlib.h` (SVID): SVID Random Number Function.

`int lcong48_r (unsigned short int param[7], struct drand48_data *buffer)`

  `stdlib.h` (GNU): SVID Random Number Function.

`struct lconv`

  `locale.h` (ISO): `localeconv`: It is portable but ….

`double ldexp (double value, int exponent)`

  `math.h` (ISO): Normalization Functions.

`float ldexpf (float value, int exponent)`

  `math.h` (ISO): Normalization Functions.

`_FloatN ldexpfN (_FloatN value, int exponent)`

  `math.h` (TS 18661-3:2015): Normalization Functions.

`_FloatNx ldexpfNx (_FloatNx value, int exponent)`

  `math.h` (TS 18661-3:2015): Normalization Functions.

`long double ldexpl (long double value, int exponent)`

  `math.h` (ISO): Normalization Functions.

`ldiv_t ldiv (long int numerator, long int denominator)`

  `stdlib.h` (ISO): Integer Division.

`ldiv_t`

  `stdlib.h` (ISO): Integer Division.

`void * lfind (const void *key, const void *base, size_t *nmemb, size_t size, comparison_fn_t compar)`

  `search.h` (SVID): Array Search Function.

`double lgamma (double x)`

  `math.h` (SVID): Special Functions.

`double lgamma_r (double x, int *signp)`

  `math.h` (XPG): Special Functions.

`float lgammaf (float x)`

  `math.h` (SVID): Special Functions.

`_FloatN lgammafN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Special Functions.

`_FloatN lgammafN_r (_FloatN x, int *signp)`

  `math.h` (GNU): Special Functions.

`_FloatNx lgammafNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Special Functions.

`_FloatNx lgammafNx_r (_FloatNx x, int *signp)`

  `math.h` (GNU): Special Functions.

`float lgammaf_r (float x, int *signp)`

  `math.h` (XPG): Special Functions.

`long double lgammal (long double x)`

  `math.h` (SVID): Special Functions.

`long double lgammal_r (long double x, int *signp)`

  `math.h` (XPG): Special Functions.

`struct linger`

  `sys/socket.h` (BSD): Socket-Level Options.

`int link (const char *oldname, const char *newname)`

  `unistd.h` (POSIX.1): Hard Links.

`int linkat (int oldfd, const char *oldname, int newfd, const char *newname, int flags)`

  `unistd.h` (POSIX.1): Hard Links.

`int lio_listio (int mode, struct aiocb *const list[], int nent, struct sigevent *sig)`

  `aio.h` (POSIX.1b): Asynchronous Read and Write Operations.

`int lio_listio64 (int mode, struct aiocb64 *const list[], int nent, struct sigevent *sig)`

  `aio.h` (Unix98): Asynchronous Read and Write Operations.

`int listen (int socket, int n)`

  `sys/socket.h` (BSD): Listening for Connections.

`long long int llabs (long long int number)`

  `stdlib.h` (ISO): Absolute Value.

`lldiv_t lldiv (long long int numerator, long long int denominator)`

  `stdlib.h` (ISO): Integer Division.

`lldiv_t`

  `stdlib.h` (ISO): Integer Division.

`long int llogb (double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`long int llogbf (float x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`long int llogbfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`long int llogbfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`long int llogbl (long double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`long long int llrint (double x)`

  `math.h` (ISO): Rounding Functions.

`long long int llrintf (float x)`

  `math.h` (ISO): Rounding Functions.

`long long int llrintfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`long long int llrintfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`long long int llrintl (long double x)`

  `math.h` (ISO): Rounding Functions.

`long long int llround (double x)`

  `math.h` (ISO): Rounding Functions.

`long long int llroundf (float x)`

  `math.h` (ISO): Rounding Functions.

`long long int llroundfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`long long int llroundfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`long long int llroundl (long double x)`

  `math.h` (ISO): Rounding Functions.

`struct lconv * localeconv (void)`

  `locale.h` (ISO): `localeconv`: It is portable but ….

`struct tm * localtime (const time_t *time)`

  `time.h` (ISO): Broken-down Time.

`struct tm * localtime_r (const time_t *time, struct tm *resultp)`

  `time.h` (POSIX.1c): Broken-down Time.

`double log (double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`double log10 (double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`float log10f (float x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`_FloatN log10fN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`_FloatNx log10fNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`long double log10l (long double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`double log10p1 (double x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`float log10p1f (float x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatN log10p1fN (_FloatN x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatNx log10p1fNx (_FloatNx x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`long double log10p1l (long double x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`double log1p (double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`float log1pf (float x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`_FloatN log1pfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`_FloatNx log1pfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`long double log1pl (long double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`double log2 (double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`float log2f (float x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`_FloatN log2fN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`_FloatNx log2fNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`long double log2l (long double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`double log2p1 (double x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`float log2p1f (float x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatN log2p1fN (_FloatN x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatNx log2p1fNx (_FloatNx x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`long double log2p1l (long double x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`double logb (double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`float logbf (float x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`_FloatN logbfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`_FloatNx logbfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`long double logbl (long double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`float logf (float x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`_FloatN logfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`_FloatNx logfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`void login (const struct utmp *entry)`

  `utmp.h` (BSD): Logging In and Out.

`int login_tty (int filedes)`

  `utmp.h` (BSD): Logging In and Out.

`long double logl (long double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`int logout (const char *ut_line)`

  `utmp.h` (BSD): Logging In and Out.

`double logp1 (double x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`float logp1f (float x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatN logp1fN (_FloatN x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatNx logp1fNx (_FloatNx x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`long double logp1l (long double x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`void logwtmp (const char *ut_line, const char *ut_name, const char *ut_host)`

  `utmp.h` (BSD): Logging In and Out.

`void longjmp (jmp_buf state, int value)`

  `setjmp.h` (ISO): Details of Non-Local Exits.

`long int lrand48 (void)`

  `stdlib.h` (SVID): SVID Random Number Function.

`int lrand48_r (struct drand48_data *buffer, long int *result)`

  `stdlib.h` (GNU): SVID Random Number Function.

`long int lrint (double x)`

  `math.h` (ISO): Rounding Functions.

`long int lrintf (float x)`

  `math.h` (ISO): Rounding Functions.

`long int lrintfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`long int lrintfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`long int lrintl (long double x)`

  `math.h` (ISO): Rounding Functions.

`long int lround (double x)`

  `math.h` (ISO): Rounding Functions.

`long int lroundf (float x)`

  `math.h` (ISO): Rounding Functions.

`long int lroundfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`long int lroundfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`long int lroundl (long double x)`

  `math.h` (ISO): Rounding Functions.

`void * lsearch (const void *key, void *base, size_t *nmemb, size_t size, comparison_fn_t compar)`

  `search.h` (SVID): Array Search Function.

`off_t lseek (int filedes, off_t offset, int whence)`

  `unistd.h` (POSIX.1): Setting the File Position of a Descriptor.

`off64_t lseek64 (int filedes, off64_t offset, int whence)`

  `unistd.h` (Unix98): Setting the File Position of a Descriptor.

`int lstat (const char *filename, struct stat *buf)`

  `sys/stat.h` (BSD): Reading the Attributes of a File.

`int lstat64 (const char *filename, struct stat64 *buf)`

  `sys/stat.h` (Unix98): Reading the Attributes of a File.

`int lutimes (const char *filename, const struct timeval tvp`[2]`)`

  `sys/time.h` (BSD): File Times.

`int madvise (void *addr, size_t length, int advice)`

  `sys/mman.h` (POSIX): Memory-mapped I/O.

`void makecontext (ucontext_t *ucp, void (*func) (void), int argc, …)`

  `ucontext.h` (SVID): Complete Context Control.

`struct mallinfo2`

  `malloc.h` (GNU): Statistics for Memory Allocation with `malloc`.

`struct mallinfo2 mallinfo2 (void)`

  `malloc.h` (SVID): Statistics for Memory Allocation with `malloc`.

`void * malloc (size_t size)`

  `malloc.h` (ISO): Basic Memory Allocation.

  `stdlib.h` (ISO): Basic Memory Allocation.

`int mblen (const char *string, size_t size)`

  `stdlib.h` (ISO): Non-reentrant Conversion of Single Characters.

`size_t mbrlen (const char *restrict s, size_t n, mbstate_t *ps)`

  `wchar.h` (ISO): Converting Single Characters.

`size_t mbrtowc (wchar_t *restrict pwc, const char *restrict s, size_t n, mbstate_t *restrict ps)`

  `wchar.h` (ISO): Converting Single Characters.

`int mbsinit (const mbstate_t *ps)`

  `wchar.h` (ISO): Representing the state of the conversion.

`size_t mbsnrtowcs (wchar_t *restrict dst, const char **restrict src, size_t nmc, size_t len, mbstate_t *restrict ps)`

  `wchar.h` (GNU): Converting Multibyte and Wide Character Strings.

`size_t mbsrtowcs (wchar_t *restrict dst, const char **restrict src, size_t len, mbstate_t *restrict ps)`

  `wchar.h` (ISO): Converting Multibyte and Wide Character Strings.

`mbstate_t`

  `wchar.h` (ISO): Representing the state of the conversion.

`size_t mbstowcs (wchar_t *wstring, const char *string, size_t size)`

  `stdlib.h` (ISO): Non-reentrant Conversion of Strings.

`int mbtowc (wchar_t *restrict result, const char *restrict string, size_t size)`

  `stdlib.h` (ISO): Non-reentrant Conversion of Single Characters.

`int mcheck (void (*abortfn) (enum mcheck_status status))`

  `mcheck.h` (GNU): Heap Consistency Checking.

`void * memalign (size_t boundary, size_t size)`

  `malloc.h` (BSD): Allocating Aligned Memory Blocks.

`size_t memalignment (void *p)`

  `stdlib.h` (C23): Allocating Aligned Memory Blocks.

`void * memccpy (void *restrict to, const void *restrict from, int c, size_t size)`

  `string.h` (SVID): Copying Strings and Arrays.

`void * memchr (const void *block, int c, size_t size)`

  `string.h` (ISO): Search Functions.

`int memcmp (const void *a1, const void *a2, size_t size)`

  `string.h` (ISO): String/Array Comparison.

`void * memcpy (void *restrict to, const void *restrict from, size_t size)`

  `string.h` (ISO): Copying Strings and Arrays.

`int memfd_create (const char *name, unsigned int flags)`

  `sys/mman.h` (Linux): Memory-mapped I/O.

`void * memfrob (void *mem, size_t length)`

  `string.h` (GNU): Obfuscating Data.

`void * memmem (const void *haystack, size_t haystack-len,
const void *needle, size_t needle-len)`

  `string.h` (POSIX.1-2024): Search Functions.

`void * memmove (void *to, const void *from, size_t size)`

  `string.h` (ISO): Copying Strings and Arrays.

`void * mempcpy (void *restrict to, const void *restrict from, size_t size)`

  `string.h` (GNU): Copying Strings and Arrays.

`void * memrchr (const void *block, int c, size_t size)`

  `string.h` (GNU): Search Functions.

`void * memset (void *block, int c, size_t size)`

  `string.h` (ISO): Copying Strings and Arrays.

`void * memset_explicit (void *block, int c, size_t size)`

  `string.h` (C23): Erasing Sensitive Data.

`int mkdir (const char *filename, mode_t mode)`

  `sys/stat.h` (POSIX.1): Creating Directories.

`int mkdirat (int filedes, const char *filename, mode_t mode)`

  `sys/stat.h` (POSIX.1-2008): Creating Directories.

`char * mkdtemp (char *template)`

  `stdlib.h` (BSD): Temporary Files.

`int mkfifo (const char *filename, mode_t mode)`

  `sys/stat.h` (POSIX.1): FIFO Special Files.

`int mknod (const char *filename, mode_t mode, dev_t dev)`

  `sys/stat.h` (BSD): Making Special Files.

`int mkstemp (char *template)`

  `stdlib.h` (BSD): Temporary Files.

`char * mktemp (char *template)`

  `stdlib.h` (Unix): Temporary Files.

`time_t mktime (struct tm *brokentime)`

  `time.h` (ISO): Broken-down Time.

`int mlock (const void *addr, size_t len)`

  `sys/mman.h` (POSIX.1b): Functions To Lock And Unlock Pages.

`int mlock2 (const void *addr, size_t len, unsigned int flags)`

  `sys/mman.h` (Linux): Functions To Lock And Unlock Pages.

`int mlockall (int flags)`

  `sys/mman.h` (POSIX.1b): Functions To Lock And Unlock Pages.

`void * mmap (void *address, size_t length, int protect, int flags, int filedes, off_t offset)`

  `sys/mman.h` (POSIX): Memory-mapped I/O.

`void * mmap64 (void *address, size_t length, int protect, int flags, int filedes, off64_t offset)`

  `sys/mman.h` (LFS): Memory-mapped I/O.

`struct mntent`

  `mntent.h` (BSD): The `mtab` file.

`mode_t`

  `sys/types.h` (POSIX.1): The meaning of the File Attributes.

`double modf (double value, double *integer-part)`

  `math.h` (ISO): Rounding Functions.

`float modff (float value, float *integer-part)`

  `math.h` (ISO): Rounding Functions.

`_FloatN modffN (_FloatN value, _FloatN *integer-part)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`_FloatNx modffNx (_FloatNx value, _FloatNx *integer-part)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`long double modfl (long double value, long double *integer-part)`

  `math.h` (ISO): Rounding Functions.

`int mount (const char *special_file, const char *dir, const char *fstype, unsigned long int options, const void *data)`

  `sys/mount.h` (SVID): Mount, Unmount, Remount.

  `sys/mount.h` (BSD): Mount, Unmount, Remount.

`int mprotect (void *address, size_t length, int protection)`

  `sys/mman.h` (POSIX): Memory Protection.

`long int mrand48 (void)`

  `stdlib.h` (SVID): SVID Random Number Function.

`int mrand48_r (struct drand48_data *buffer, long int *result)`

  `stdlib.h` (GNU): SVID Random Number Function.

`void * mremap (void *address, size_t length, size_t new_length, int flag, ... /* void *new_address */)`

  `sys/mman.h` (GNU): Memory-mapped I/O.

`int mseal (void *address, size_t length, unsigned long flags)`

  `sys/mman.h` (Linux): Memory Protection.

`struct msghdr`

  `sys/socket.h` (BSD): Other Socket APIs.

`int msync (void *address, size_t length, int flags)`

  `sys/mman.h` (POSIX): Memory-mapped I/O.

`void mtrace (void)`

  `mcheck.h` (GNU): How to install the tracing functionality.

`void mtx_destroy (mtx_t *mutex)`

  `threads.h` (C11): Mutexes.

`int mtx_init (mtx_t *mutex, int type)`

  `threads.h` (C11): Mutexes.

`int mtx_lock (mtx_t *mutex)`

  `threads.h` (C11): Mutexes.

`mtx_plain`

  `threads.h` (C11): Mutexes.

`mtx_recursive`

  `threads.h` (C11): Mutexes.

`mtx_t`

  `threads.h` (C11): Mutexes.

`mtx_timed`

  `threads.h` (C11): Mutexes.

`int mtx_timedlock (mtx_t *restrict mutex, const struct timespec *restrict time_point)`

  `threads.h` (C11): Mutexes.

`int mtx_trylock (mtx_t *mutex)`

  `threads.h` (C11): Mutexes.

`int mtx_unlock (mtx_t *mutex)`

  `threads.h` (C11): Mutexes.

`int munlock (const void *addr, size_t len)`

  `sys/mman.h` (POSIX.1b): Functions To Lock And Unlock Pages.

`int munlockall (void)`

  `sys/mman.h` (POSIX.1b): Functions To Lock And Unlock Pages.

`int munmap (void *addr, size_t length)`

  `sys/mman.h` (POSIX): Memory-mapped I/O.

`void muntrace (void)`

  `mcheck.h` (GNU): How to install the tracing functionality.

`double nan (const char *tagp)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`float nanf (const char *tagp)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`_FloatN nanfN (const char *tagp)`

  `math.h` (TS 18661-3:2015): Setting and modifying single bits of FP values.

`_FloatNx nanfNx (const char *tagp)`

  `math.h` (TS 18661-3:2015): Setting and modifying single bits of FP values.

`long double nanl (const char *tagp)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`int nanosleep (const struct timespec *requested_time, struct timespec *remaining_time)`

  `time.h` (POSIX.1): Sleeping.

`double nearbyint (double x)`

  `math.h` (ISO): Rounding Functions.

`float nearbyintf (float x)`

  `math.h` (ISO): Rounding Functions.

`_FloatN nearbyintfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`_FloatNx nearbyintfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`long double nearbyintl (long double x)`

  `math.h` (ISO): Rounding Functions.

`struct netent`

  `netdb.h` (BSD): Networks Database.

`double nextafter (double x, double y)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`float nextafterf (float x, float y)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`_FloatN nextafterfN (_FloatN x, _FloatN y)`

  `math.h` (TS 18661-3:2015): Setting and modifying single bits of FP values.

`_FloatNx nextafterfNx (_FloatNx x, _FloatNx y)`

  `math.h` (TS 18661-3:2015): Setting and modifying single bits of FP values.

`long double nextafterl (long double x, long double y)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`double nextdown (double x)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`float nextdownf (float x)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`_FloatN nextdownfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Setting and modifying single bits of FP values.

`_FloatNx nextdownfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Setting and modifying single bits of FP values.

`long double nextdownl (long double x)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`double nexttoward (double x, long double y)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`float nexttowardf (float x, long double y)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`long double nexttowardl (long double x, long double y)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`double nextup (double x)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`float nextupf (float x)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`_FloatN nextupfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Setting and modifying single bits of FP values.

`_FloatNx nextupfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Setting and modifying single bits of FP values.

`long double nextupl (long double x)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`int nftw (const char *filename, __nftw_func_t func, int descriptors, int flag)`

  `ftw.h` (XPG4.2): Working with Directory Trees.

`int nftw64 (const char *filename, __nftw64_func_t func, int descriptors, int flag)`

  `ftw.h` (Unix98): Working with Directory Trees.

`char * ngettext (const char *msgid1, const char *msgid2, unsigned long int n)`

  `libintl.h` (POSIX-1.2024): Additional functions for more complicated situations.

`int nice (int increment)`

  `unistd.h` (BSD): Functions For Traditional Scheduling.

`char * nl_langinfo (nl_item item)`

  `langinfo.h` (XOPEN): Pinpoint Access to Locale Data.

`nlink_t`

  `sys/types.h` (POSIX.1): The meaning of the File Attributes.

`long int nrand48 (unsigned short int xsubi[3])`

  `stdlib.h` (SVID): SVID Random Number Function.

`int nrand48_r (unsigned short int xsubi[3], struct drand48_data *buffer, long int *result)`

  `stdlib.h` (GNU): SVID Random Number Function.

`uint32_t ntohl (uint32_t netlong)`

  `netinet/in.h` (BSD): Byte Order Conversion.

`uint16_t ntohs (uint16_t netshort)`

  `netinet/in.h` (BSD): Byte Order Conversion.

`int ntp_adjtime (struct timex *tptr)`

  `sys/timex.h` (GNU): Setting and Adjusting the Time.

`int ntp_gettime (struct ntptimeval *tptr)`

  `sys/timex.h` (GNU): Setting and Adjusting the Time.

`struct obstack`

  `obstack.h` (GNU): Creating Obstacks.

`void obstack_1grow (struct obstack *obstack-ptr, char c)`

  `obstack.h` (GNU): Growing Objects.

`void obstack_1grow_fast (struct obstack *obstack-ptr, char c)`

  `obstack.h` (GNU): Extra Fast Growing Objects.

`int obstack_alignment_mask (struct obstack *obstack-ptr)`

  `obstack.h` (GNU): Alignment of Data in Obstacks.

`void * obstack_alloc (struct obstack *obstack-ptr, int size)`

  `obstack.h` (GNU): Allocation in an Obstack.

`obstack_alloc_failed_handler`

  `obstack.h` (GNU): Preparing for Using Obstacks.

`void * obstack_base (struct obstack *obstack-ptr)`

  `obstack.h` (GNU): Status of an Obstack.

`void obstack_blank (struct obstack *obstack-ptr, int size)`

  `obstack.h` (GNU): Growing Objects.

`void obstack_blank_fast (struct obstack *obstack-ptr, int size)`

  `obstack.h` (GNU): Extra Fast Growing Objects.

`int obstack_chunk_size (struct obstack *obstack-ptr)`

  `obstack.h` (GNU): Obstack Chunks.

`void * obstack_copy (struct obstack *obstack-ptr, void *address, int size)`

  `obstack.h` (GNU): Allocation in an Obstack.

`void * obstack_copy0 (struct obstack *obstack-ptr, void *address, int size)`

  `obstack.h` (GNU): Allocation in an Obstack.

`void * obstack_finish (struct obstack *obstack-ptr)`

  `obstack.h` (GNU): Growing Objects.

`void obstack_free (struct obstack *obstack-ptr, void *object)`

  `obstack.h` (GNU): Freeing Objects in an Obstack.

`void obstack_grow (struct obstack *obstack-ptr, void *data, int size)`

  `obstack.h` (GNU): Growing Objects.

`void obstack_grow0 (struct obstack *obstack-ptr, void *data, int size)`

  `obstack.h` (GNU): Growing Objects.

`int obstack_init (struct obstack *obstack-ptr)`

  `obstack.h` (GNU): Preparing for Using Obstacks.

`void obstack_int_grow (struct obstack *obstack-ptr, int data)`

  `obstack.h` (GNU): Growing Objects.

`void obstack_int_grow_fast (struct obstack *obstack-ptr, int data)`

  `obstack.h` (GNU): Extra Fast Growing Objects.

`void * obstack_next_free (struct obstack *obstack-ptr)`

  `obstack.h` (GNU): Status of an Obstack.

`int obstack_object_size (struct obstack *obstack-ptr)`

  `obstack.h` (GNU): Growing Objects.

  `obstack.h` (GNU): Status of an Obstack.

`int obstack_printf (struct obstack *obstack, const char *template, …)`

  `stdio.h` (GNU): Dynamically Allocating Formatted Output.

`void obstack_ptr_grow (struct obstack *obstack-ptr, void *data)`

  `obstack.h` (GNU): Growing Objects.

`void obstack_ptr_grow_fast (struct obstack *obstack-ptr, void *data)`

  `obstack.h` (GNU): Extra Fast Growing Objects.

`int obstack_room (struct obstack *obstack-ptr)`

  `obstack.h` (GNU): Extra Fast Growing Objects.

`int obstack_vprintf (struct obstack *obstack, const char *template, va_list ap)`

  `stdio.h` (GNU): Variable Arguments Output Functions.

`off64_t`

  `sys/types.h` (Unix98): Setting the File Position of a Descriptor.

`off_t`

  `sys/types.h` (POSIX.1): Setting the File Position of a Descriptor.

`size_t offsetof (type, member)`

  `stddef.h` (ISO): Structure Field Offset Measurement.

`int on_exit (void (*function)(int status, void *arg), void *arg)`

  `stdlib.h` (SunOS): Cleanups on Exit.

`once_flag`

  `threads.h` (C11): Call Once.

`int open (const char *filename, int flags[, mode_t mode])`

  `fcntl.h` (POSIX.1): Opening and Closing Files.

`int open64 (const char *filename, int flags[, mode_t mode])`

  `fcntl.h` (Unix98): Opening and Closing Files.

`struct open_how`

  `fcntl.h` (Linux): Opening and Closing Files.

`FILE * open_memstream (char **ptr, size_t *sizeloc)`

  `stdio.h` (GNU): String Streams.

`int openat (int filedes, const char *filename, int flags[, mode_t mode])`

  `fcntl.h` (POSIX.1): Opening and Closing Files.

`int openat2 (int dirfd, const char *pathname, const struct open_how *how, size_t size)`

  `fcntl.h` (Linux): Opening and Closing Files.

`int openat64 (int filedes, const char *filename, int flags[, mode_t mode])`

  `fcntl.h` (GNU): Opening and Closing Files.

`DIR * opendir (const char *dirname)`

  `dirent.h` (POSIX.1): Opening a Directory Stream.

`void openlog (const char *ident, int option, int facility)`

  `syslog.h` (BSD): openlog.

`int openpty (int *amaster, int *aslave, char *name, const struct termios *termp, const struct winsize *winp)`

  `pty.h` (BSD): Opening a Pseudo-Terminal Pair.

`char * optarg`

  `unistd.h` (POSIX.2): Using the `getopt` function.

`int opterr`

  `unistd.h` (POSIX.2): Using the `getopt` function.

`int optind`

  `unistd.h` (POSIX.2): Using the `getopt` function.

`struct option`

  `getopt.h` (GNU): Parsing Long Options with `getopt_long`.

`int optopt`

  `unistd.h` (POSIX.2): Using the `getopt` function.

`size_t parse_printf_format (const char *template, size_t n, int *argtypes)`

  `printf.h` (GNU): Parsing a Template String.

`struct passwd`

  `pwd.h` (POSIX.1): The Data Structure that Describes a User.

`long int pathconf (const char *filename, int parameter)`

  `unistd.h` (POSIX.1): Using `pathconf`.

`int pause (void)`

  `unistd.h` (POSIX.1): Using `pause`.

`int pclose (FILE *stream)`

  `stdio.h` (POSIX.2): Pipe to a Subprocess.

  `stdio.h` (SVID): Pipe to a Subprocess.

  `stdio.h` (BSD): Pipe to a Subprocess.

`void perror (const char *message)`

  `stdio.h` (ISO): Error Messages.

`pid_t`

  `sys/types.h` (POSIX.1): Process Identification.

`pid_t pidfd_getpid (int fd)`

  `sys/pidfd.h` (GNU): Querying a Process.

`int pipe (int filedes`[2]`)`

  `unistd.h` (POSIX.1): Creating a Pipe.

`int pkey_alloc (unsigned int flags, unsigned int access_restrictions)`

  `sys/mman.h` (Linux): Memory Protection.

`int pkey_free (int key)`

  `sys/mman.h` (Linux): Memory Protection.

`int pkey_get (int key)`

  `sys/mman.h` (Linux): Memory Protection.

`int pkey_mprotect (void *address, size_t length, int protection, int key)`

  `sys/mman.h` (Linux): Memory Protection.

`int pkey_set (int key, unsigned int access_restrictions)`

  `sys/mman.h` (Linux): Memory Protection.

`FILE * popen (const char *command, const char *mode)`

  `stdio.h` (POSIX.2): Pipe to a Subprocess.

  `stdio.h` (SVID): Pipe to a Subprocess.

  `stdio.h` (BSD): Pipe to a Subprocess.

`int posix_memalign (void **memptr, size_t alignment, size_t size)`

  `stdlib.h` (POSIX): Allocating Aligned Memory Blocks.

`int posix_openpt (int flags)`

  `stdlib.h` (POSIX.1): Allocating Pseudo-Terminals.

`double pow (double base, double power)`

  `math.h` (ISO): Exponentiation and Logarithms.

`float powf (float base, float power)`

  `math.h` (ISO): Exponentiation and Logarithms.

`_FloatN powfN (_FloatN base, _FloatN power)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`_FloatNx powfNx (_FloatNx base, _FloatNx power)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`long double powl (long double base, long double power)`

  `math.h` (ISO): Exponentiation and Logarithms.

`double pown (double base, long long int power)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`float pownf (float base, long long int power)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatN pownfN (_FloatN base, long long int power)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatNx pownfNx (_FloatNx base, long long int power)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`long double pownl (long double base, long long int power)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`double powr (double base, double power)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`float powrf (float base, float power)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatN powrfN (_FloatN base, _FloatN power)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatNx powrfNx (_FloatNx base, _FloatNx power)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`long double powrl (long double base, long double power)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`ssize_t pread (int filedes, void *buffer, size_t size, off_t offset)`

  `unistd.h` (Unix98): Input and Output Primitives.

`ssize_t pread64 (int filedes, void *buffer, size_t size, off64_t offset)`

  `unistd.h` (Unix98): Input and Output Primitives.

`ssize_t preadv (int fd, const struct iovec *iov, int iovcnt, off_t offset)`

  `sys/uio.h` (BSD): Fast Scatter-Gather I/O.

`ssize_t preadv2 (int fd, const struct iovec *iov, int iovcnt, off_t offset, int flags)`

  `sys/uio.h` (GNU): Fast Scatter-Gather I/O.

`ssize_t preadv64 (int fd, const struct iovec *iov, int iovcnt, off64_t offset)`

  `unistd.h` (BSD): Fast Scatter-Gather I/O.

`ssize_t preadv64v2 (int fd, const struct iovec *iov, int iovcnt, off64_t offset, int flags)`

  `unistd.h` (GNU): Fast Scatter-Gather I/O.

`int printf (const char *template, …)`

  `stdio.h` (ISO): Formatted Output Functions.

`printf_arginfo_function`

  `printf.h` (GNU): Defining the Output Handler.

`printf_function`

  `printf.h` (GNU): Defining the Output Handler.

`struct printf_info`

  `printf.h` (GNU): Conversion Specifier Options.

`int printf_size (FILE *fp, const struct printf_info *info, const void *const *args)`

  `printf.h` (GNU): Predefined `printf` Handlers.

`int printf_size_info (const struct printf_info *info, size_t n, int *argtypes)`

  `printf.h` (GNU): Predefined `printf` Handlers.

`char * program_invocation_name`

  `errno.h` (GNU): Error Messages.

`char * program_invocation_short_name`

  `errno.h` (GNU): Error Messages.

`struct protoent`

  `netdb.h` (BSD): Protocols Database.

`void psignal (int signum, const char *message)`

  `signal.h` (BSD): Signal Messages.

`int pthread_attr_getsigmask_np (const pthread_attr_t *attr, sigset_t *sigmask)`

  `pthread.h` (GNU): Controlling the Initial Signal Mask of a New Thread.

`int pthread_attr_setsigmask_np (pthread_attr_t *attr, const sigset_t *sigmask)`

  `pthread.h` (GNU): Controlling the Initial Signal Mask of a New Thread.

`int pthread_barrier_destroy (pthread_barrier_t *barrier)`

  `pthread.h` (POSIX): POSIX Barriers.

`int pthread_barrier_init (pthread_barrier_t *barrier, const pthread_barrierattr_t *attr, unsigned int count)`

  `pthread.h` (POSIX): POSIX Barriers.

`int pthread_barrier_wait (pthread_barrier_t *barrier)`

  `pthread.h` (POSIX): POSIX Barriers.

`int pthread_clockjoin_np (pthread_t *thread, void **thread_return, clockid_t clockid, const struct timespec *abstime)`

  `pthread.h` (GNU): Wait for a thread to terminate.

`int pthread_cond_clockwait (pthread_cond_t *cond, pthread_mutex_t *mutex, clockid_t clockid, const struct timespec *abstime)`

  `pthread.h` (POSIX-1.2024): Functions for Waiting According to a Specific Clock.

`int pthread_getattr_default_np (pthread_attr_t *attr)`

  `pthread.h` (GNU): Setting Process-wide defaults for thread attributes.

`void * pthread_getspecific (pthread_key_t key)`

  `pthread.h` (POSIX): Thread-specific Data.

`pid_t pthread_gettid_np (pthread_t thread)`

  `pthread.h` (Linux): Process Identification.

`int pthread_key_create (pthread_key_t *key, void (*destructor)(void*))`

  `pthread.h` (POSIX): Thread-specific Data.

`int pthread_key_delete (pthread_key_t key)`

  `pthread.h` (POSIX): Thread-specific Data.

`int pthread_rwlock_clockrdlock (pthread_rwlock_t *rwlock, clockid_t clockid, const struct timespec *abstime)`

  `pthread.h` (POSIX-1.2024): Functions for Waiting According to a Specific Clock.

`int pthread_rwlock_clockwrlock (pthread_rwlock_t *rwlock, clockid_t clockid, const struct timespec *abstime)`

  `pthread.h` (POSIX-1.2024): Functions for Waiting According to a Specific Clock.

`int pthread_setattr_default_np (pthread_attr_t *attr)`

  `pthread.h` (GNU): Setting Process-wide defaults for thread attributes.

`int pthread_setspecific (pthread_key_t key, const void *value)`

  `pthread.h` (POSIX): Thread-specific Data.

`int pthread_timedjoin_np (pthread_t *thread, void **thread_return, const struct timespec *abstime)`

  `pthread.h` (GNU): Wait for a thread to terminate.

`int pthread_tryjoin_np (pthread_t *thread, void **thread_return)`

  `pthread.h` (GNU): Wait for a thread to terminate.

`ptrdiff_t`

  `stddef.h` (ISO): Important Data Types.

`char * ptsname (int filedes)`

  `stdlib.h` (SVID): Allocating Pseudo-Terminals.

  `stdlib.h` (XPG4.2): Allocating Pseudo-Terminals.

`int ptsname_r (int filedes, char *buf, size_t len)`

  `stdlib.h` (POSIX.1-2024): Allocating Pseudo-Terminals.

`int putc (int c, FILE *stream)`

  `stdio.h` (ISO): Simple Output by Characters or Lines.

`int putc_unlocked (int c, FILE *stream)`

  `stdio.h` (POSIX): Simple Output by Characters or Lines.

`int putchar (int c)`

  `stdio.h` (ISO): Simple Output by Characters or Lines.

`int putchar_unlocked (int c)`

  `stdio.h` (POSIX): Simple Output by Characters or Lines.

`int putenv (char *string)`

  `stdlib.h` (SVID): Environment Access.

`int putpwent (const struct passwd *p, FILE *stream)`

  `pwd.h` (SVID): Writing a User Entry.

`int puts (const char *s)`

  `stdio.h` (ISO): Simple Output by Characters or Lines.

`struct utmp * pututline (const struct utmp *utmp)`

  `utmp.h` (SVID): Manipulating the User Accounting Database.

`struct utmpx * pututxline (const struct utmpx *utmp)`

  `utmpx.h` (XPG4.2): XPG User Accounting Database Functions.

`int putw (int w, FILE *stream)`

  `stdio.h` (SVID): Simple Output by Characters or Lines.

`wint_t putwc (wchar_t wc, FILE *stream)`

  `wchar.h` (ISO): Simple Output by Characters or Lines.

`wint_t putwc_unlocked (wchar_t wc, FILE *stream)`

  `wchar.h` (GNU): Simple Output by Characters or Lines.

`wint_t putwchar (wchar_t wc)`

  `wchar.h` (ISO): Simple Output by Characters or Lines.

`wint_t putwchar_unlocked (wchar_t wc)`

  `wchar.h` (GNU): Simple Output by Characters or Lines.

`ssize_t pwrite (int filedes, const void *buffer, size_t size, off_t offset)`

  `unistd.h` (Unix98): Input and Output Primitives.

`ssize_t pwrite64 (int filedes, const void *buffer, size_t size, off64_t offset)`

  `unistd.h` (Unix98): Input and Output Primitives.

`ssize_t pwritev (int fd, const struct iovec *iov, int iovcnt, off_t offset)`

  `sys/uio.h` (BSD): Fast Scatter-Gather I/O.

`ssize_t pwritev2 (int fd, const struct iovec *iov, int iovcnt, off_t offset, int flags)`

  `sys/uio.h` (GNU): Fast Scatter-Gather I/O.

`ssize_t pwritev64 (int fd, const struct iovec *iov, int iovcnt, off64_t offset)`

  `unistd.h` (BSD): Fast Scatter-Gather I/O.

`ssize_t pwritev64v2 (int fd, const struct iovec *iov, int iovcnt, off64_t offset, int flags)`

  `unistd.h` (GNU): Fast Scatter-Gather I/O.

`char * qecvt (long double value, int ndigit, int *decpt, int *neg)`

  `stdlib.h` (GNU): Old-fashioned System V number-to-string functions.

`int qecvt_r (long double value, int ndigit, int *decpt, int *neg, char *buf, size_t len)`

  `stdlib.h` (GNU): Old-fashioned System V number-to-string functions.

`char * qfcvt (long double value, int ndigit, int *decpt, int *neg)`

  `stdlib.h` (GNU): Old-fashioned System V number-to-string functions.

`int qfcvt_r (long double value, int ndigit, int *decpt, int *neg, char *buf, size_t len)`

  `stdlib.h` (GNU): Old-fashioned System V number-to-string functions.

`char * qgcvt (long double value, int ndigit, char *buf)`

  `stdlib.h` (GNU): Old-fashioned System V number-to-string functions.

`void qsort (void *array, size_t count, size_t size, comparison_fn_t compare)`

  `stdlib.h` (ISO): Array Sort Function.

`int raise (int signum)`

  `signal.h` (ISO): Signaling Yourself.

`int rand (void)`

  `stdlib.h` (ISO): ISO C Random Number Functions.

`int rand_r (unsigned int *seed)`

  `stdlib.h` (POSIX.1): ISO C Random Number Functions.

`long int random (void)`

  `stdlib.h` (BSD): BSD Random Number Functions.

`struct random_data`

  `stdlib.h` (GNU): BSD Random Number Functions.

`int random_r (struct random_data *restrict buf, int32_t *restrict result)`

  `stdlib.h` (GNU): BSD Random Number Functions.

`void * rawmemchr (const void *block, int c)`

  `string.h` (GNU): Search Functions.

`ssize_t read (int filedes, void *buffer, size_t size)`

  `unistd.h` (POSIX.1): Input and Output Primitives.

`struct dirent * readdir (DIR *dirstream)`

  `dirent.h` (POSIX.1): Reading and Closing a Directory Stream.

`struct dirent64 * readdir64 (DIR *dirstream)`

  `dirent.h` (LFS): Reading and Closing a Directory Stream.

`int readdir64_r (DIR *dirstream, struct dirent64 *entry, struct dirent64 **result)`

  `dirent.h` (LFS): Reading and Closing a Directory Stream.

`int readdir_r (DIR *dirstream, struct dirent *entry, struct dirent **result)`

  `dirent.h` (GNU): Reading and Closing a Directory Stream.

`ssize_t readlink (const char *filename, char *buffer, size_t size)`

  `unistd.h` (BSD): Symbolic Links.

`ssize_t readv (int filedes, const struct iovec *vector, int count)`

  `sys/uio.h` (BSD): Fast Scatter-Gather I/O.

`void * realloc (void *ptr, size_t newsize)`

  `malloc.h` (ISO): Changing the Size of a Block.

  `stdlib.h` (ISO): Changing the Size of a Block.

`void * reallocarray (void *ptr, size_t nmemb, size_t size)`

  `malloc.h` (POSIX.1-2024): Changing the Size of a Block.

  `stdlib.h` (POSIX.1-2024): Changing the Size of a Block.

`char * realpath (const char *restrict name, char *restrict resolved)`

  `stdlib.h` (XPG): Symbolic Links.

`ssize_t recv (int socket, void *buffer, size_t size, int flags)`

  `sys/socket.h` (BSD): Receiving Data.

`ssize_t recvfrom (int socket, void *buffer, size_t size, int flags, struct sockaddr *addr, socklen_t *length-ptr)`

  `sys/socket.h` (BSD): Receiving Datagrams.

`int regcomp (regex_t *restrict compiled, const char *restrict pattern, int cflags)`

  `regex.h` (POSIX.2): POSIX Regular Expression Compilation.

`size_t regerror (int errcode, const regex_t *restrict compiled, char *restrict buffer, size_t length)`

  `regex.h` (POSIX.2): POSIX Regexp Matching Cleanup.

`regex_t`

  `regex.h` (POSIX.2): POSIX Regular Expression Compilation.

`int regexec (const regex_t *restrict compiled, const char *restrict string, size_t nmatch, regmatch_t matchptr[restrict], int eflags)`

  `regex.h` (POSIX.2): Matching a Compiled POSIX Regular Expression.

`void regfree (regex_t *compiled)`

  `regex.h` (POSIX.2): POSIX Regexp Matching Cleanup.

`int register_printf_function (int spec, printf_function handler-function, printf_arginfo_function arginfo-function)`

  `printf.h` (GNU): Registering New Conversions.

`regmatch_t`

  `regex.h` (POSIX.2): Match Results with Subexpressions.

`regoff_t`

  `regex.h` (POSIX.2): Match Results with Subexpressions.

`double remainder (double numerator, double denominator)`

  `math.h` (ISO): Remainder Functions.

`float remainderf (float numerator, float denominator)`

  `math.h` (ISO): Remainder Functions.

`_FloatN remainderfN (_FloatN numerator, _FloatN denominator)`

  `math.h` (TS 18661-3:2015): Remainder Functions.

`_FloatNx remainderfNx (_FloatNx numerator, _FloatNx denominator)`

  `math.h` (TS 18661-3:2015): Remainder Functions.

`long double remainderl (long double numerator, long double denominator)`

  `math.h` (ISO): Remainder Functions.

`int remove (const char *filename)`

  `stdio.h` (ISO): Deleting Files.

`int rename (const char *oldname, const char *newname)`

  `stdio.h` (ISO): Renaming Files.

`int renameat (int oldfiledes, const char *oldname, int newfiledes, const char *newname)`

  `stdio.h` (POSIX.1-2008): Renaming Files.

`void rewind (FILE *stream)`

  `stdio.h` (ISO): File Positioning.

`void rewinddir (DIR *dirstream)`

  `dirent.h` (POSIX.1): Random Access in a Directory Stream.

`char * rindex (const char *string, int c)`

  `string.h` (BSD): Search Functions.

`double rint (double x)`

  `math.h` (ISO): Rounding Functions.

`float rintf (float x)`

  `math.h` (ISO): Rounding Functions.

`_FloatN rintfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`_FloatNx rintfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`long double rintl (long double x)`

  `math.h` (ISO): Rounding Functions.

`struct rlimit`

  `sys/resource.h` (BSD): Limiting Resource Usage.

`struct rlimit64`

  `sys/resource.h` (Unix98): Limiting Resource Usage.

`int rmdir (const char *filename)`

  `unistd.h` (POSIX.1): Deleting Files.

`double rootn (double x, long long int n)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`float rootnf (float x, long long int n)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatN rootnfN (_FloatN x, long long int n)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatNx rootnfNx (_FloatNx x, long long int n)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`long double rootnl (long double x, long long int n)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`double round (double x)`

  `math.h` (ISO): Rounding Functions.

`double roundeven (double x)`

  `math.h` (ISO): Rounding Functions.

`float roundevenf (float x)`

  `math.h` (ISO): Rounding Functions.

`_FloatN roundevenfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`_FloatNx roundevenfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`long double roundevenl (long double x)`

  `math.h` (ISO): Rounding Functions.

`float roundf (float x)`

  `math.h` (ISO): Rounding Functions.

`_FloatN roundfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`_FloatNx roundfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`long double roundl (long double x)`

  `math.h` (ISO): Rounding Functions.

`int rpmatch (const char *response)`

  `stdlib.h` (GNU): Yes-or-No Questions.

`struct rseq`

  `sys/rseq.h` (Linux): Restartable Sequences.

`double rsqrt (double x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`float rsqrtf (float x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatN rsqrtfN (_FloatN x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`_FloatNx rsqrtfNx (_FloatNx x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`long double rsqrtl (long double x)`

  `math.h` (TS 18661-4:2015): Exponentiation and Logarithms.

`struct rusage`

  `sys/resource.h` (BSD): Resource Usage.

`void * sbrk (ptrdiff_t delta)`

  `unistd.h` (BSD): Resizing the Data Segment.

`double scalb (double value, double exponent)`

  `math.h` (BSD): Normalization Functions.

`float scalbf (float value, float exponent)`

  `math.h` (BSD): Normalization Functions.

`long double scalbl (long double value, long double exponent)`

  `math.h` (BSD): Normalization Functions.

`double scalbln (double x, long int n)`

  `math.h` (BSD): Normalization Functions.

`float scalblnf (float x, long int n)`

  `math.h` (BSD): Normalization Functions.

`_FloatN scalblnfN (_FloatN x, long int n)`

  `math.h` (TS 18661-3:2015): Normalization Functions.

`_FloatNx scalblnfNx (_FloatNx x, long int n)`

  `math.h` (TS 18661-3:2015): Normalization Functions.

`long double scalblnl (long double x, long int n)`

  `math.h` (BSD): Normalization Functions.

`double scalbn (double x, int n)`

  `math.h` (BSD): Normalization Functions.

`float scalbnf (float x, int n)`

  `math.h` (BSD): Normalization Functions.

`_FloatN scalbnfN (_FloatN x, int n)`

  `math.h` (TS 18661-3:2015): Normalization Functions.

`_FloatNx scalbnfNx (_FloatNx x, int n)`

  `math.h` (TS 18661-3:2015): Normalization Functions.

`long double scalbnl (long double x, int n)`

  `math.h` (BSD): Normalization Functions.

`int scandir (const char *dir, struct dirent ***namelist, int (*selector) (const struct dirent *), int (*cmp) (const struct dirent **, const struct dirent **))`

  `dirent.h` (BSD): Scanning the Content of a Directory.

  `dirent.h` (SVID): Scanning the Content of a Directory.

`int scandir64 (const char *dir, struct dirent64 ***namelist, int (*selector) (const struct dirent64 *), int (*cmp) (const struct dirent64 **, const struct dirent64 **))`

  `dirent.h` (GNU): Scanning the Content of a Directory.

`int scanf (const char *template, …)`

  `stdio.h` (ISO): Formatted Input Functions.

`struct sched_attr`

  `sched.h` (Linux): Extensible Scheduling.

`int sched_get_priority_max (int policy)`

  `sched.h` (POSIX): Basic Scheduling Functions.

`int sched_get_priority_min (int policy)`

  `sched.h` (POSIX): Basic Scheduling Functions.

`int sched_getaffinity (pid_t pid, size_t cpusetsize, cpu_set_t *cpuset)`

  `sched.h` (GNU): Limiting execution to certain CPUs.

`int sched_getattr (pid_t tid, struct sched_attr *attr, unsigned int size, unsigned int flags)`

  `sched.h` (Linux): Extensible Scheduling.

`int sched_getcpu (void)`

  `<sched.h>` (Linux): Limiting execution to certain CPUs.

`int sched_getparam (pid_t pid, struct sched_param *param)`

  `sched.h` (POSIX): Basic Scheduling Functions.

`int sched_getscheduler (pid_t pid)`

  `sched.h` (POSIX): Basic Scheduling Functions.

`struct sched_param`

  `sched.h` (POSIX): Basic Scheduling Functions.

`int sched_rr_get_interval (pid_t pid, struct timespec *interval)`

  `sched.h` (POSIX): Basic Scheduling Functions.

`int sched_setaffinity (pid_t pid, size_t cpusetsize, const cpu_set_t *cpuset)`

  `sched.h` (GNU): Limiting execution to certain CPUs.

`int sched_setattr (pid_t tid, struct sched_attr *attr, unsigned int flags)`

  `sched.h` (Linux): Extensible Scheduling.

`int sched_setparam (pid_t pid, const struct sched_param *param)`

  `sched.h` (POSIX): Basic Scheduling Functions.

`int sched_setscheduler (pid_t pid, int policy, const struct sched_param *param)`

  `sched.h` (POSIX): Basic Scheduling Functions.

`int sched_yield (void)`

  `sched.h` (POSIX): Basic Scheduling Functions.

`char * secure_getenv (const char *name)`

  `stdlib.h` (POSIX.1-2024): Environment Access.

`unsigned short int * seed48 (unsigned short int seed16v[3])`

  `stdlib.h` (SVID): SVID Random Number Function.

`int seed48_r (unsigned short int seed16v[3], struct drand48_data *buffer)`

  `stdlib.h` (GNU): SVID Random Number Function.

`void seekdir (DIR *dirstream, long int pos)`

  `dirent.h` (BSD): Random Access in a Directory Stream.

`int select (int nfds, fd_set *read-fds, fd_set *write-fds, fd_set *except-fds, struct timeval *timeout)`

  `sys/select.h` (POSIX.1): Waiting for Input or Output.

`int sem_clockwait (sem_t *sem, clockid_t clockid, const struct timespec *abstime)`

  `semaphore.h` (POSIX.1-2024): POSIX Semaphores.

`int sem_close (sem_t *sem)`

  `semaphore.h` (POSIX.1-2008): POSIX Semaphores.

`int sem_destroy (sem_t *sem)`

  `semaphore.h` (POSIX.1-2008): POSIX Semaphores.

`int sem_getvalue (sem_t *sem, int *sval)`

  `semaphore.h` (POSIX.1-2008): POSIX Semaphores.

`int sem_init (sem_t *sem, int pshared, unsigned int value)`

  `semaphore.h` (POSIX.1-2008): POSIX Semaphores.

`sem_t * sem_open (const char *name, int oflag, ...)`

  `semaphore.h` (POSIX.1-2008): POSIX Semaphores.

`int sem_post (sem_t *sem)`

  `semaphore.h` (POSIX.1-2008): POSIX Semaphores.

`int sem_timedwait (sem_t *sem, const struct timespec *abstime)`

  `semaphore.h` (POSIX.1-2008): POSIX Semaphores.

`int sem_trywait (sem_t *sem)`

  `semaphore.h` (POSIX.1-2008): POSIX Semaphores.

`int sem_unlink (const char *name)`

  `semaphore.h` (POSIX.1-2008): POSIX Semaphores.

`int sem_wait (sem_t *sem)`

  `semaphore.h` (POSIX.1-2008): POSIX Semaphores.

`ssize_t send (int socket, const void *buffer, size_t size, int flags)`

  `sys/socket.h` (BSD): Sending Data.

`ssize_t sendto (int socket, const void *buffer, size_t size, int flags, struct sockaddr *addr, socklen_t length)`

  `sys/socket.h` (BSD): Sending Datagrams.

`struct servent`

  `netdb.h` (BSD): The Services Database.

`void setbuf (FILE *stream, char *buf)`

  `stdio.h` (ISO): Controlling Which Kind of Buffering.

`void setbuffer (FILE *stream, char *buf, size_t size)`

  `stdio.h` (BSD): Controlling Which Kind of Buffering.

`int setcontext (const ucontext_t *ucp)`

  `ucontext.h` (SVID): Complete Context Control.

`int setdomainname (const char *name, size_t length)`

  `unistd.h` (???): Host Identification.

`int setegid (gid_t newgid)`

  `unistd.h` (POSIX.1): Setting the Group IDs.

`int setenv (const char *name, const char *value, int replace)`

  `stdlib.h` (BSD): Environment Access.

`int seteuid (uid_t neweuid)`

  `unistd.h` (POSIX.1): Setting the User ID.

`int setfsent (void)`

  `fstab.h` (BSD): The `fstab` file.

`int setgid (gid_t newgid)`

  `unistd.h` (POSIX.1): Setting the Group IDs.

`void setgrent (void)`

  `grp.h` (SVID): Scanning the List of All Groups.

  `grp.h` (BSD): Scanning the List of All Groups.

`int setgroups (size_t count, const gid_t *groups)`

  `grp.h` (BSD): Setting the Group IDs.

`void sethostent (int stayopen)`

  `netdb.h` (BSD): Host Names.

`int sethostid (long int id)`

  `unistd.h` (BSD): Host Identification.

`int sethostname (const char *name, size_t length)`

  `unistd.h` (BSD): Host Identification.

`int setitimer (int which, const struct itimerval *new, struct itimerval *old)`

  `sys/time.h` (BSD): Setting an Alarm.

`int setjmp (jmp_buf state)`

  `setjmp.h` (ISO): Details of Non-Local Exits.

`void setlinebuf (FILE *stream)`

  `stdio.h` (BSD): Controlling Which Kind of Buffering.

`char * setlocale (int category, const char *locale)`

  `locale.h` (ISO): How Programs Set the Locale.

`int setlogmask (int mask)`

  `syslog.h` (BSD): setlogmask.

`FILE * setmntent (const char *file, const char *mode)`

  `mntent.h` (BSD): The `mtab` file.

`void setnetent (int stayopen)`

  `netdb.h` (BSD): Networks Database.

`int setnetgrent (const char *netgroup)`

  `netdb.h` (BSD): Looking up one Netgroup.

`int setpayload (double *x, double payload)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`int setpayloadf (float *x, float payload)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`int setpayloadfN (_FloatN *x, _FloatN payload)`

  `math.h` (TS 18661-3:2015): Setting and modifying single bits of FP values.

`int setpayloadfNx (_FloatNx *x, _FloatNx payload)`

  `math.h` (TS 18661-3:2015): Setting and modifying single bits of FP values.

`int setpayloadl (long double *x, long double payload)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`int setpayloadsig (double *x, double payload)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`int setpayloadsigf (float *x, float payload)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`int setpayloadsigfN (_FloatN *x, _FloatN payload)`

  `math.h` (TS 18661-3:2015): Setting and modifying single bits of FP values.

`int setpayloadsigfNx (_FloatNx *x, _FloatNx payload)`

  `math.h` (TS 18661-3:2015): Setting and modifying single bits of FP values.

`int setpayloadsigl (long double *x, long double payload)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`int setpgid (pid_t pid, pid_t pgid)`

  `unistd.h` (POSIX.1): Process Group Functions.

`int setpgrp (pid_t pid, pid_t pgid)`

  `unistd.h` (BSD): Process Group Functions.

`int setpriority (int class, int id, int niceval)`

  `sys/resource.h` (BSD): Functions For Traditional Scheduling.

  `sys/resource.h` (POSIX): Functions For Traditional Scheduling.

`void setprotoent (int stayopen)`

  `netdb.h` (BSD): Protocols Database.

`void setpwent (void)`

  `pwd.h` (SVID): Scanning the List of All Users.

  `pwd.h` (BSD): Scanning the List of All Users.

`int setregid (gid_t rgid, gid_t egid)`

  `unistd.h` (BSD): Setting the Group IDs.

`int setreuid (uid_t ruid, uid_t euid)`

  `unistd.h` (BSD): Setting the User ID.

`int setrlimit (int resource, const struct rlimit *rlp)`

  `sys/resource.h` (BSD): Limiting Resource Usage.

`int setrlimit64 (int resource, const struct rlimit64 *rlp)`

  `sys/resource.h` (Unix98): Limiting Resource Usage.

`void setservent (int stayopen)`

  `netdb.h` (BSD): The Services Database.

`pid_t setsid (void)`

  `unistd.h` (POSIX.1): Process Group Functions.

`int setsockopt (int socket, int level, int optname, const void *optval, socklen_t optlen)`

  `sys/socket.h` (BSD): Socket Option Functions.

`char * setstate (char *state)`

  `stdlib.h` (BSD): BSD Random Number Functions.

`int setstate_r (char *restrict statebuf, struct random_data *restrict buf)`

  `stdlib.h` (GNU): BSD Random Number Functions.

`int settimeofday (const struct timeval *tp, const void *tzp)`

  `sys/time.h` (BSD): Setting and Adjusting the Time.

`int setuid (uid_t newuid)`

  `unistd.h` (POSIX.1): Setting the User ID.

`void setutent (void)`

  `utmp.h` (SVID): Manipulating the User Accounting Database.

`void setutxent (void)`

  `utmpx.h` (XPG4.2): XPG User Accounting Database Functions.

`int setvbuf (FILE *stream, char *buf, int mode, size_t size)`

  `stdio.h` (ISO): Controlling Which Kind of Buffering.

`struct sgttyb`

  `termios.h` (BSD): BSD Terminal Modes.

`int shm_open (const char *name, int oflag, mode_t mode)`

  `sys/mman.h` (POSIX): Memory-mapped I/O.

`int shutdown (int socket, int how)`

  `sys/socket.h` (BSD): Closing a Socket.

`sig_atomic_t`

  `signal.h` (ISO): Atomic Types.

`const char * sigabbrev_np (int signum)`

  `string.h` (GNU): Signal Messages.

`int sigaction (int signum, const struct sigaction *restrict action, struct sigaction *restrict old-action)`

  `signal.h` (POSIX.1): Advanced Signal Handling.

`struct sigaction`

  `signal.h` (POSIX.1): Advanced Signal Handling.

`int sigaddset (sigset_t *set, int signum)`

  `signal.h` (POSIX.1): Signal Sets.

`int sigaltstack (const stack_t *restrict stack, stack_t *restrict oldstack)`

  `signal.h` (XPG): Using a Separate Signal Stack.

`int sigblock (int mask)`

  `signal.h` (BSD): BSD Signal Handling.

`int sigdelset (sigset_t *set, int signum)`

  `signal.h` (POSIX.1): Signal Sets.

`const char * sigdescr_np (int signum)`

  `string.h` (GNU): Signal Messages.

`int sigemptyset (sigset_t *set)`

  `signal.h` (POSIX.1): Signal Sets.

`int sigfillset (sigset_t *set)`

  `signal.h` (POSIX.1): Signal Sets.

`sighandler_t`

  `signal.h` (GNU): Basic Signal Handling.

`int siginterrupt (int signum, int failflag)`

  `signal.h` (XPG): BSD Signal Handling.

`int sigismember (const sigset_t *set, int signum)`

  `signal.h` (POSIX.1): Signal Sets.

`sigjmp_buf`

  `setjmp.h` (POSIX.1): Non-Local Exits and Signals.

`void siglongjmp (sigjmp_buf state, int value)`

  `setjmp.h` (POSIX.1): Non-Local Exits and Signals.

`int sigmask (int signum)`

  `signal.h` (BSD): BSD Signal Handling.

`sighandler_t signal (int signum, sighandler_t action)`

  `signal.h` (ISO): Basic Signal Handling.

`int signbit (float-type x)`

  `math.h` (ISO): Setting and modifying single bits of FP values.

`double significand (double x)`

  `math.h` (BSD): Normalization Functions.

`float significandf (float x)`

  `math.h` (BSD): Normalization Functions.

`long double significandl (long double x)`

  `math.h` (BSD): Normalization Functions.

`int sigpause (int mask)`

  `signal.h` (BSD): BSD Signal Handling.

`int sigpending (sigset_t *set)`

  `signal.h` (POSIX.1): Checking for Pending Signals.

`int sigprocmask (int how, const sigset_t *restrict set, sigset_t *restrict oldset)`

  `signal.h` (POSIX.1): Process Signal Mask.

`sigset_t`

  `signal.h` (POSIX.1): Signal Sets.

`int sigsetjmp (sigjmp_buf state, int savesigs)`

  `setjmp.h` (POSIX.1): Non-Local Exits and Signals.

`int sigsetmask (int mask)`

  `signal.h` (BSD): BSD Signal Handling.

`int sigstack (struct sigstack *stack, struct sigstack *oldstack)`

  `signal.h` (BSD): Using a Separate Signal Stack.

`struct sigstack`

  `signal.h` (BSD): Using a Separate Signal Stack.

`int sigsuspend (const sigset_t *set)`

  `signal.h` (POSIX.1): Using `sigsuspend`.

`double sin (double x)`

  `math.h` (ISO): Trigonometric Functions.

`void sincos (double x, double *sinx, double *cosx)`

  `math.h` (GNU): Trigonometric Functions.

`void sincosf (float x, float *sinx, float *cosx)`

  `math.h` (GNU): Trigonometric Functions.

`_FloatN sincosfN (_FloatN x, _FloatN *sinx, _FloatN *cosx)`

  `math.h` (GNU): Trigonometric Functions.

`_FloatNx sincosfNx (_FloatNx x, _FloatNx *sinx, _FloatNx *cosx)`

  `math.h` (GNU): Trigonometric Functions.

`void sincosl (long double x, long double *sinx, long double *cosx)`

  `math.h` (GNU): Trigonometric Functions.

`float sinf (float x)`

  `math.h` (ISO): Trigonometric Functions.

`_FloatN sinfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Trigonometric Functions.

`_FloatNx sinfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Trigonometric Functions.

`double sinh (double x)`

  `math.h` (ISO): Hyperbolic Functions.

`float sinhf (float x)`

  `math.h` (ISO): Hyperbolic Functions.

`_FloatN sinhfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Hyperbolic Functions.

`_FloatNx sinhfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Hyperbolic Functions.

`long double sinhl (long double x)`

  `math.h` (ISO): Hyperbolic Functions.

`long double sinl (long double x)`

  `math.h` (ISO): Trigonometric Functions.

`double sinpi (double x)`

  `math.h` (TS 18661-4:2015): Trigonometric Functions.

`float sinpif (float x)`

  `math.h` (TS 18661-4:2015): Trigonometric Functions.

`_FloatN sinpifN (_FloatN x)`

  `math.h` (TS 18661-4:2015): Trigonometric Functions.

`_FloatNx sinpifNx (_FloatNx x)`

  `math.h` (TS 18661-4:2015): Trigonometric Functions.

`long double sinpil (long double x)`

  `math.h` (TS 18661-4:2015): Trigonometric Functions.

`size_t`

  `stddef.h` (ISO): Important Data Types.

`unsigned int sleep (unsigned int seconds)`

  `unistd.h` (POSIX.1): Sleeping.

`int snprintf (char *s, size_t size, const char *template, …)`

  `stdio.h` (GNU): Formatted Output Functions.

`struct sockaddr`

  `sys/socket.h` (BSD): Address Formats.

`struct sockaddr_in`

  `netinet/in.h` (BSD): Internet Socket Address Formats.

`struct sockaddr_un`

  `sys/un.h` (BSD): Details of Local Namespace.

`int socket (int namespace, int style, int protocol)`

  `sys/socket.h` (BSD): Creating a Socket.

`int socketpair (int namespace, int style, int protocol, int filedes`[2]`)`

  `sys/socket.h` (BSD): Socket Pairs.

`speed_t`

  `termios.h` (POSIX.1): Line Speed.

`int sprintf (char *s, const char *template, …)`

  `stdio.h` (ISO): Formatted Output Functions.

`double sqrt (double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`float sqrtf (float x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`_FloatN sqrtfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`_FloatNx sqrtfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Exponentiation and Logarithms.

`long double sqrtl (long double x)`

  `math.h` (ISO): Exponentiation and Logarithms.

`void srand (unsigned int seed)`

  `stdlib.h` (ISO): ISO C Random Number Functions.

`void srand48 (long int seedval)`

  `stdlib.h` (SVID): SVID Random Number Function.

`int srand48_r (long int seedval, struct drand48_data *buffer)`

  `stdlib.h` (GNU): SVID Random Number Function.

`void srandom (unsigned int seed)`

  `stdlib.h` (BSD): BSD Random Number Functions.

`int srandom_r (unsigned int seed, struct random_data *buf)`

  `stdlib.h` (GNU): BSD Random Number Functions.

`int sscanf (const char *s, const char *template, …)`

  `stdio.h` (ISO): Formatted Input Functions.

`sighandler_t ssignal (int signum, sighandler_t action)`

  `signal.h` (SVID): Basic Signal Handling.

`ssize_t`

  `unistd.h` (POSIX.1): Input and Output Primitives.

`stack_t`

  `signal.h` (XPG): Using a Separate Signal Stack.

`int stat (const char *filename, struct stat *buf)`

  `sys/stat.h` (POSIX.1): Reading the Attributes of a File.

`struct stat`

  `sys/stat.h` (POSIX.1): The meaning of the File Attributes.

`int stat64 (const char *filename, struct stat64 *buf)`

  `sys/stat.h` (Unix98): Reading the Attributes of a File.

`struct stat64`

  `sys/stat.h` (LFS): The meaning of the File Attributes.

`unsigned char stdc_bit_ceil_uc (unsigned char x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_bit_ceil_ui (unsigned int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned long int stdc_bit_ceil_ul (unsigned long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned long long int stdc_bit_ceil_ull (unsigned long long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned short stdc_bit_ceil_us (unsigned short x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned char stdc_bit_floor_uc (unsigned char x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_bit_floor_ui (unsigned int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned long int stdc_bit_floor_ul (unsigned long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned long long int stdc_bit_floor_ull (unsigned long long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned short stdc_bit_floor_us (unsigned short x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_bit_width_uc (unsigned char x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_bit_width_ui (unsigned int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_bit_width_ul (unsigned long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_bit_width_ull (unsigned long long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_bit_width_us (unsigned short x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_count_ones_uc (unsigned char x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_count_ones_ui (unsigned int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_count_ones_ul (unsigned long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_count_ones_ull (unsigned long long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_count_ones_us (unsigned short x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_count_zeros_uc (unsigned char x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_count_zeros_ui (unsigned int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_count_zeros_ul (unsigned long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_count_zeros_ull (unsigned long long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_count_zeros_us (unsigned short x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_first_leading_one_uc (unsigned char x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_first_leading_one_ui (unsigned int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_first_leading_one_ul (unsigned long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_first_leading_one_ull (unsigned long long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_first_leading_one_us (unsigned short x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_first_leading_zero_uc (unsigned char x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_first_leading_zero_ui (unsigned int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_first_leading_zero_ul (unsigned long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_first_leading_zero_ull (unsigned long long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_first_leading_zero_us (unsigned short x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_first_trailing_one_uc (unsigned char x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_first_trailing_one_ui (unsigned int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_first_trailing_one_ul (unsigned long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_first_trailing_one_ull (unsigned long long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_first_trailing_one_us (unsigned short x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_first_trailing_zero_uc (unsigned char x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_first_trailing_zero_ui (unsigned int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_first_trailing_zero_ul (unsigned long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_first_trailing_zero_ull (unsigned long long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_first_trailing_zero_us (unsigned short x)`

  `stdbit.h` (C23): Bit Manipulation.

`_Bool stdc_has_single_bit_uc (unsigned char x)`

  `stdbit.h` (C23): Bit Manipulation.

`_Bool stdc_has_single_bit_ui (unsigned int x)`

  `stdbit.h` (C23): Bit Manipulation.

`_Bool stdc_has_single_bit_ul (unsigned long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`_Bool stdc_has_single_bit_ull (unsigned long long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`_Bool stdc_has_single_bit_us (unsigned short x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_leading_ones_uc (unsigned char x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_leading_ones_ui (unsigned int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_leading_ones_ul (unsigned long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_leading_ones_ull (unsigned long long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_leading_ones_us (unsigned short x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_leading_zeros_uc (unsigned char x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_leading_zeros_ui (unsigned int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_leading_zeros_ul (unsigned long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_leading_zeros_ull (unsigned long long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_leading_zeros_us (unsigned short x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_trailing_ones_uc (unsigned char x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_trailing_ones_ui (unsigned int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_trailing_ones_ul (unsigned long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_trailing_ones_ull (unsigned long long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_trailing_ones_us (unsigned short x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_trailing_zeros_uc (unsigned char x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_trailing_zeros_ui (unsigned int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_trailing_zeros_ul (unsigned long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_trailing_zeros_ull (unsigned long long int x)`

  `stdbit.h` (C23): Bit Manipulation.

`unsigned int stdc_trailing_zeros_us (unsigned short x)`

  `stdbit.h` (C23): Bit Manipulation.

`FILE * stderr`

  `stdio.h` (ISO): Standard Streams.

`FILE * stdin`

  `stdio.h` (ISO): Standard Streams.

`FILE * stdout`

  `stdio.h` (ISO): Standard Streams.

`int stime (const time_t *newtime)`

  `time.h` (SVID): Setting and Adjusting the Time.

  `time.h` (XPG): Setting and Adjusting the Time.

`char * stpcpy (char *restrict to, const char *restrict from)`

  `string.h` (Unknown origin): Copying Strings and Arrays.

`char * stpncpy (char *restrict to, const char *restrict from, size_t size)`

  `string.h` (GNU): Truncating Strings while Copying.

`int strcasecmp (const char *s1, const char *s2)`

  `string.h` (BSD): String/Array Comparison.

`char * strcasestr (const char *haystack, const char *needle)`

  `string.h` (GNU): Search Functions.

`char * strcat (char *restrict to, const char *restrict from)`

  `string.h` (ISO): Concatenating Strings.

`char * strchr (const char *string, int c)`

  `string.h` (ISO): Search Functions.

`char * strchrnul (const char *string, int c)`

  `string.h` (GNU): Search Functions.

`int strcmp (const char *s1, const char *s2)`

  `string.h` (ISO): String/Array Comparison.

`int strcoll (const char *s1, const char *s2)`

  `string.h` (ISO): Collation Functions.

`char * strcpy (char *restrict to, const char *restrict from)`

  `string.h` (ISO): Copying Strings and Arrays.

`size_t strcspn (const char *string, const char *stopset)`

  `string.h` (ISO): Search Functions.

`char * strdup (const char *s)`

  `string.h` (SVID): Copying Strings and Arrays.

`char * strdupa (const char *s)`

  `string.h` (GNU): Copying Strings and Arrays.

`char * strerror (int errnum)`

  `string.h` (ISO): Error Messages.

`char * strerror_l (int errnum, locale_t locale)`

  `string.h` (POSIX): Error Messages.

`char * strerror_r (int errnum, char *buf, size_t n)`

  `string.h` (GNU): Error Messages.

`int strerror_r (int errnum, char *buf, size_t n)`

  `string.h` (POSIX): Error Messages.

`const char * strerrordesc_np (int errnum)`

  `string.h` (GNU): Error Messages.

`const char * strerrorname_np (int errnum)`

  `string.h` (GNU): Error Messages.

`int strfromd (char *restrict string, size_t size, const char *restrict format, double value)`

  `stdlib.h` (ISO/IEC TS 18661-1): Printing of Floats.

`int strfromf (char *restrict string, size_t size, const char *restrict format, float value)`

  `stdlib.h` (ISO/IEC TS 18661-1): Printing of Floats.

`int strfromfN (char *restrict string, size_t size, const char *restrict format, _FloatN value)`

  `stdlib.h` (ISO/IEC TS 18661-3): Printing of Floats.

`int strfromfNx (char *restrict string, size_t size, const char *restrict format, _FloatNx value)`

  `stdlib.h` (ISO/IEC TS 18661-3): Printing of Floats.

`int strfroml (char *restrict string, size_t size, const char *restrict format, long double value)`

  `stdlib.h` (ISO/IEC TS 18661-1): Printing of Floats.

`char * strfry (char *string)`

  `string.h` (GNU): Shuffling Bytes.

`size_t strftime (char *s, size_t size, const char *template, const struct tm *brokentime)`

  `time.h` (ISO): Formatting Calendar Time.

`size_t strftime_l (char *restrict s, size_t size, const char *restrict template, const struct tm *brokentime, locale_t locale)`

  `time.h` (POSIX.1): Formatting Calendar Time.

`size_t strlcat (char *restrict to, const char *restrict from, size_t size)`

  `string.h` (POSIX-1.2024): Truncating Strings while Copying.

`size_t strlcpy (char *restrict to, const char *restrict from, size_t size)`

  `string.h` (POSIX-1.2024): Truncating Strings while Copying.

`size_t strlen (const char *s)`

  `string.h` (ISO): String Length.

`int strncasecmp (const char *s1, const char *s2, size_t n)`

  `string.h` (BSD): String/Array Comparison.

`char * strncat (char *restrict to, const char *restrict from, size_t size)`

  `string.h` (ISO): Truncating Strings while Copying.

`int strncmp (const char *s1, const char *s2, size_t size)`

  `string.h` (ISO): String/Array Comparison.

`char * strncpy (char *restrict to, const char *restrict from, size_t size)`

  `string.h` (C90): Truncating Strings while Copying.

`char * strndup (const char *s, size_t size)`

  `string.h` (GNU): Truncating Strings while Copying.

`char * strndupa (const char *s, size_t size)`

  `string.h` (GNU): Truncating Strings while Copying.

`size_t strnlen (const char *s, size_t maxlen)`

  `string.h` (POSIX.1): String Length.

`char * strpbrk (const char *string, const char *stopset)`

  `string.h` (ISO): Search Functions.

`char * strptime (const char *s, const char *fmt, struct tm *tp)`

  `time.h` (XPG4): Interpret string according to given format.

`char * strrchr (const char *string, int c)`

  `string.h` (ISO): Search Functions.

`char * strsep (char **string_ptr, const char *delimiter)`

  `string.h` (BSD): Finding Tokens in a String.

`char * strsignal (int signum)`

  `string.h` (GNU): Signal Messages.

`size_t strspn (const char *string, const char *skipset)`

  `string.h` (ISO): Search Functions.

`char * strstr (const char *haystack, const char *needle)`

  `string.h` (ISO): Search Functions.

`double strtod (const char *restrict string, char **restrict tailptr)`

  `stdlib.h` (ISO): Parsing of Floats.

`float strtof (const char *string, char **tailptr)`

  `stdlib.h` (ISO): Parsing of Floats.

`_FloatN strtofN (const char *string, char **tailptr)`

  `stdlib.h` (ISO/IEC TS 18661-3): Parsing of Floats.

`_FloatNx strtofNx (const char *string, char **tailptr)`

  `stdlib.h` (ISO/IEC TS 18661-3): Parsing of Floats.

`intmax_t strtoimax (const char *restrict string, char **restrict tailptr, int base)`

  `inttypes.h` (ISO): Parsing of Integers.

`char * strtok (char *restrict newstring, const char *restrict delimiters)`

  `string.h` (ISO): Finding Tokens in a String.

`char * strtok_r (char *newstring, const char *delimiters, char **save_ptr)`

  `string.h` (POSIX): Finding Tokens in a String.

`long int strtol (const char *restrict string, char **restrict tailptr, int base)`

  `stdlib.h` (ISO): Parsing of Integers.

`long double strtold (const char *string, char **tailptr)`

  `stdlib.h` (ISO): Parsing of Floats.

`long long int strtoll (const char *restrict string, char **restrict tailptr, int base)`

  `stdlib.h` (ISO): Parsing of Integers.

`long long int strtoq (const char *restrict string, char **restrict tailptr, int base)`

  `stdlib.h` (BSD): Parsing of Integers.

`unsigned long int strtoul (const char *restrict string, char **restrict tailptr, int base)`

  `stdlib.h` (ISO): Parsing of Integers.

`unsigned long long int strtoull (const char *restrict string, char **restrict tailptr, int base)`

  `stdlib.h` (ISO): Parsing of Integers.

`uintmax_t strtoumax (const char *restrict string, char **restrict tailptr, int base)`

  `inttypes.h` (ISO): Parsing of Integers.

`unsigned long long int strtouq (const char *restrict string, char **restrict tailptr, int base)`

  `stdlib.h` (BSD): Parsing of Integers.

`int strverscmp (const char *s1, const char *s2)`

  `string.h` (GNU): String/Array Comparison.

`size_t strxfrm (char *restrict to, const char *restrict from, size_t size)`

  `string.h` (ISO): Collation Functions.

`int stty (int filedes, const struct sgttyb *attributes)`

  `sgtty.h` (BSD): BSD Terminal Modes.

`int swapcontext (ucontext_t *restrict oucp, const ucontext_t *restrict ucp)`

  `ucontext.h` (SVID): Complete Context Control.

`int swprintf (wchar_t *ws, size_t size, const wchar_t *template, …)`

  `wchar.h` (GNU): Formatted Output Functions.

`int swscanf (const wchar_t *ws, const wchar_t *template, …)`

  `wchar.h` (ISO): Formatted Input Functions.

`int symlink (const char *oldname, const char *newname)`

  `unistd.h` (BSD): Symbolic Links.

`void sync (void)`

  `unistd.h` (X/Open): Synchronizing I/O operations.

`long int syscall (long int sysno, …)`

  `unistd.h` (???): System Calls.

`long int sysconf (int parameter)`

  `unistd.h` (POSIX.1): Definition of `sysconf`.

`void syslog (int facility_priority, const char *format, …)`

  `syslog.h` (BSD): syslog, vsyslog.

`int system (const char *command)`

  `stdlib.h` (ISO): Running a Command.

`sighandler_t sysv_signal (int signum, sighandler_t action)`

  `signal.h` (GNU): Basic Signal Handling.

`double tan (double x)`

  `math.h` (ISO): Trigonometric Functions.

`float tanf (float x)`

  `math.h` (ISO): Trigonometric Functions.

`_FloatN tanfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Trigonometric Functions.

`_FloatNx tanfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Trigonometric Functions.

`double tanh (double x)`

  `math.h` (ISO): Hyperbolic Functions.

`float tanhf (float x)`

  `math.h` (ISO): Hyperbolic Functions.

`_FloatN tanhfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Hyperbolic Functions.

`_FloatNx tanhfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Hyperbolic Functions.

`long double tanhl (long double x)`

  `math.h` (ISO): Hyperbolic Functions.

`long double tanl (long double x)`

  `math.h` (ISO): Trigonometric Functions.

`double tanpi (double x)`

  `math.h` (TS 18661-4:2015): Trigonometric Functions.

`float tanpif (float x)`

  `math.h` (TS 18661-4:2015): Trigonometric Functions.

`_FloatN tanpifN (_FloatN x)`

  `math.h` (TS 18661-4:2015): Trigonometric Functions.

`_FloatNx tanpifNx (_FloatNx x)`

  `math.h` (TS 18661-4:2015): Trigonometric Functions.

`long double tanpil (long double x)`

  `math.h` (TS 18661-4:2015): Trigonometric Functions.

`int tcdrain (int filedes)`

  `termios.h` (POSIX.1): Line Control Functions.

`tcflag_t`

  `termios.h` (POSIX.1): Terminal Mode Data Types.

`int tcflow (int filedes, int action)`

  `termios.h` (POSIX.1): Line Control Functions.

`int tcflush (int filedes, int queue)`

  `termios.h` (POSIX.1): Line Control Functions.

`int tcgetattr (int filedes, struct termios *termios-p)`

  `termios.h` (POSIX.1): Terminal Mode Functions.

`pid_t tcgetpgrp (int filedes)`

  `unistd.h` (POSIX.1): Functions for Controlling Terminal Access.

`pid_t tcgetsid (int fildes)`

  `termios.h` (Unix98): Functions for Controlling Terminal Access.

`int tcsendbreak (int filedes, int duration)`

  `termios.h` (POSIX.1): Line Control Functions.

`int tcsetattr (int filedes, int when, const struct termios *termios-p)`

  `termios.h` (POSIX.1): Terminal Mode Functions.

`int tcsetpgrp (int filedes, pid_t pgid)`

  `unistd.h` (POSIX.1): Functions for Controlling Terminal Access.

`void * tdelete (const void *key, void **rootp, comparison_fn_t compar)`

  `search.h` (SVID): The `tsearch` function..

`void tdestroy (void *vroot, __free_fn_t freefct)`

  `search.h` (GNU): The `tsearch` function..

`long int telldir (DIR *dirstream)`

  `dirent.h` (BSD): Random Access in a Directory Stream.

`char * tempnam (const char *dir, const char *prefix)`

  `stdio.h` (SVID): Temporary Files.

`struct termios`

  `termios.h` (POSIX.1): Terminal Mode Data Types.

`char * textdomain (const char *domainname)`

  `libintl.h` (POSIX-1.2024): How to determine which catalog to be used.

`void * tfind (const void *key, void *const *rootp, comparison_fn_t compar)`

  `search.h` (SVID): The `tsearch` function..

`double tgamma (double x)`

  `math.h` (XPG): Special Functions.

  `math.h` (ISO): Special Functions.

`float tgammaf (float x)`

  `math.h` (XPG): Special Functions.

  `math.h` (ISO): Special Functions.

`_FloatN tgammafN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Special Functions.

`_FloatNx tgammafNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Special Functions.

`long double tgammal (long double x)`

  `math.h` (XPG): Special Functions.

  `math.h` (ISO): Special Functions.

`int tgkill (pid_t pid, pid_t tid, int signum)`

  `signal.h` (Linux): Signaling Another Process.

`thrd_busy`

  `threads.h` (C11): Return Values.

`int thrd_create (thrd_t *thr, thrd_start_t func, void *arg)`

  `threads.h` (C11): Creation and Control.

`thrd_t thrd_current (void)`

  `threads.h` (C11): Creation and Control.

`int thrd_detach (thrd_t thr)`

  `threads.h` (C11): Creation and Control.

`int thrd_equal (thrd_t lhs, thrd_t rhs)`

  `threads.h` (C11): Creation and Control.

`thrd_error`

  `threads.h` (C11): Return Values.

`_Noreturn void thrd_exit (int res)`

  `threads.h` (C11): Creation and Control.

`int thrd_join (thrd_t thr, int *res)`

  `threads.h` (C11): Creation and Control.

`thrd_nomem`

  `threads.h` (C11): Return Values.

`int thrd_sleep (const struct timespec *time_point, struct timespec *remaining)`

  `threads.h` (C11): Creation and Control.

`thrd_start_t`

  `threads.h` (C11): Creation and Control.

`thrd_success`

  `threads.h` (C11): Return Values.

`thrd_t`

  `threads.h` (C11): Creation and Control.

`thrd_timedout`

  `threads.h` (C11): Return Values.

`void thrd_yield (void)`

  `threads.h` (C11): Creation and Control.

`thread_local`

  `threads.h` (C11): Thread-local Storage.

`time_t time (time_t *result)`

  `time.h` (ISO): Getting the Time.

`time_t`

  `time.h` (ISO): Time Types.

`time_t timegm (struct tm *brokentime)`

  `time.h` (ISO): Broken-down Time.

`time_t timelocal (struct tm *brokentime)`

  `time.h` (???): Broken-down Time.

`clock_t times (struct tms *buffer)`

  `sys/times.h` (POSIX.1): Processor Time Inquiry.

`struct timespec`

  `time.h` (POSIX.1): Time Types.

`int timespec_get (struct timespec *ts, int base)`

  `time.h` (ISO): Getting the Time.

`int timespec_getres (struct timespec *res, int base)`

  `time.h` (ISO): Getting the Time.

`struct timeval`

  `sys/time.h` (BSD): Time Types.

`long int timezone`

  `time.h` (POSIX.1): State Variables for Time Zones.

`struct tm`

  `time.h` (ISO): Time Types.

  `time.h` (ISO): Broken-down Time.

`FILE * tmpfile (void)`

  `stdio.h` (ISO): Temporary Files.

`FILE * tmpfile64 (void)`

  `stdio.h` (Unix98): Temporary Files.

`char * tmpnam (char *result)`

  `stdio.h` (ISO): Temporary Files.

`char * tmpnam_r (char *result)`

  `stdio.h` (GNU): Temporary Files.

`struct tms`

  `sys/times.h` (POSIX.1): Processor Time Inquiry.

`int toascii (int c)`

  `ctype.h` (SVID): Case Conversion.

  `ctype.h` (BSD): Case Conversion.

`int tolower (int c)`

  `ctype.h` (ISO): Case Conversion.

`int totalorder (const double *x, const double *y)`

  `math.h` (TS 18661-1:2014): Floating-Point Comparison Functions.

`int totalorderf (const float *x, const float *y)`

  `math.h` (TS 18661-1:2014): Floating-Point Comparison Functions.

`int totalorderfN (const _FloatN *x, const _FloatN *y)`

  `math.h` (TS 18661-3:2015): Floating-Point Comparison Functions.

`int totalorderfNx (const _FloatNx *x, const _FloatNx *y)`

  `math.h` (TS 18661-3:2015): Floating-Point Comparison Functions.

`int totalorderl (const long double *x, const long double *y)`

  `math.h` (TS 18661-1:2014): Floating-Point Comparison Functions.

`int totalordermag (const double *x, const double *y)`

  `math.h` (TS 18661-1:2014): Floating-Point Comparison Functions.

`int totalordermagf (const float *x, const float *y)`

  `math.h` (TS 18661-1:2014): Floating-Point Comparison Functions.

`int totalordermagfN (const _FloatN *x, const _FloatN *y)`

  `math.h` (TS 18661-3:2015): Floating-Point Comparison Functions.

`int totalordermagfNx (const _FloatNx *x, const _FloatNx *y)`

  `math.h` (TS 18661-3:2015): Floating-Point Comparison Functions.

`int totalordermagl (const long double *x, const long double *y)`

  `math.h` (TS 18661-1:2014): Floating-Point Comparison Functions.

`int toupper (int c)`

  `ctype.h` (ISO): Case Conversion.

`wint_t towctrans (wint_t wc, wctrans_t desc)`

  `wctype.h` (ISO): Mapping of wide characters..

`wint_t towlower (wint_t wc)`

  `wctype.h` (ISO): Mapping of wide characters..

`wint_t towupper (wint_t wc)`

  `wctype.h` (ISO): Mapping of wide characters..

`double trunc (double x)`

  `math.h` (ISO): Rounding Functions.

`int truncate (const char *filename, off_t length)`

  `unistd.h` (X/Open): File Size.

`int truncate64 (const char *name, off64_t length)`

  `unistd.h` (Unix98): File Size.

`float truncf (float x)`

  `math.h` (ISO): Rounding Functions.

`_FloatN truncfN (_FloatN x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`_FloatNx truncfNx (_FloatNx x)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`long double truncl (long double x)`

  `math.h` (ISO): Rounding Functions.

`void * tsearch (const void *key, void **rootp, comparison_fn_t compar)`

  `search.h` (SVID): The `tsearch` function..

`int tss_create (tss_t *tss_key, tss_dtor_t destructor)`

  `threads.h` (C11): Thread-local Storage.

`void tss_delete (tss_t tss_key)`

  `threads.h` (C11): Thread-local Storage.

`tss_dtor_t`

  `threads.h` (C11): Thread-local Storage.

`void * tss_get (tss_t tss_key)`

  `threads.h` (C11): Thread-local Storage.

`int tss_set (tss_t tss_key, void *val)`

  `threads.h` (C11): Thread-local Storage.

`tss_t`

  `threads.h` (C11): Thread-local Storage.

`char * ttyname (int filedes)`

  `unistd.h` (POSIX.1): Identifying Terminals.

`int ttyname_r (int filedes, char *buf, size_t len)`

  `unistd.h` (POSIX.1): Identifying Terminals.

`void twalk (const void *root, __action_fn_t action)`

  `search.h` (SVID): The `tsearch` function..

`void twalk_r (const void *root, void (*action) (const void *key, VISIT which, void *closure), void *closure)`

  `search.h` (GNU): The `tsearch` function..

`char * tzname [2]`

  `time.h` (POSIX.1): State Variables for Time Zones.

`void tzset (void)`

  `time.h` (POSIX.1): State Variables for Time Zones.

`unsigned int uabs (int number)`

  `stdlib.h` (ISO): Absolute Value.

`ucontext_t`

  `ucontext.h` (SVID): Complete Context Control.

`double ufromfp (double x, int round, unsigned int width)`

  `math.h` (ISO): Rounding Functions.

`float ufromfpf (float x, int round, unsigned int width)`

  `math.h` (ISO): Rounding Functions.

`_FloatN ufromfpfN (_FloatN x, int round, unsigned int width)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`_FloatNx ufromfpfNx (_FloatNx x, int round, unsigned int width)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`long double ufromfpl (long double x, int round, unsigned int width)`

  `math.h` (ISO): Rounding Functions.

`double ufromfpx (double x, int round, unsigned int width)`

  `math.h` (ISO): Rounding Functions.

`float ufromfpxf (float x, int round, unsigned int width)`

  `math.h` (ISO): Rounding Functions.

`_FloatN ufromfpxfN (_FloatN x, int round, unsigned int width)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`_FloatNx ufromfpxfNx (_FloatNx x, int round, unsigned int width)`

  `math.h` (TS 18661-3:2015): Rounding Functions.

`long double ufromfpxl (long double x, int round, unsigned int width)`

  `math.h` (ISO): Rounding Functions.

`uid_t`

  `sys/types.h` (POSIX.1): Reading the Persona of a Process.

`unsigned long int ulabs (long int number)`

  `stdlib.h` (ISO): Absolute Value.

`long int ulimit (int cmd, …)`

  `ulimit.h` (BSD): Limiting Resource Usage.

`unsigned long long int ullabs (long long int number)`

  `stdlib.h` (ISO): Absolute Value.

`mode_t umask (mode_t mask)`

  `sys/stat.h` (POSIX.1): Assigning File Permissions.

`uintmax_t umaxabs (intmax_t number)`

  `inttypes.h` (ISO): Absolute Value.

`int umount (const char *file)`

  `sys/mount.h` (SVID): Mount, Unmount, Remount.

  `sys/mount.h` (GNU): Mount, Unmount, Remount.

`int umount2 (const char *file, int flags)`

  `sys/mount.h` (GNU): Mount, Unmount, Remount.

`int uname (struct utsname *info)`

  `sys/utsname.h` (POSIX.1): Platform Type Identification.

`int ungetc (int c, FILE *stream)`

  `stdio.h` (ISO): Using `ungetc` To Do Unreading.

`wint_t ungetwc (wint_t wc, FILE *stream)`

  `wchar.h` (ISO): Using `ungetc` To Do Unreading.

`int unlink (const char *filename)`

  `unistd.h` (POSIX.1): Deleting Files.

`int unlinkat (int filedes, const char *filename, int flags)`

  `unistd.h` (POSIX.1-2008): Deleting Files.

`int unlockpt (int filedes)`

  `stdlib.h` (SVID): Allocating Pseudo-Terminals.

  `stdlib.h` (XPG4.2): Allocating Pseudo-Terminals.

`int unsetenv (const char *name)`

  `stdlib.h` (BSD): Environment Access.

`void updwtmp (const char *wtmp_file, const struct utmp *utmp)`

  `utmp.h` (SVID): Manipulating the User Accounting Database.

`struct utimbuf`

  `utime.h` (POSIX.1): File Times.

`int utime (const char *filename, const struct utimbuf *times)`

  `utime.h` (POSIX.1): File Times.

`int utimensat (int filedes, const char *filename, const struct timespec tsp`[2]`, int flags)`

  `sys/stat.h` (POSIX.1-2008): File Times.

`int utimes (const char *filename, const struct timeval tvp`[2]`)`

  `sys/time.h` (BSD): File Times.

`int utmpname (const char *file)`

  `utmp.h` (SVID): Manipulating the User Accounting Database.

`int utmpxname (const char *file)`

  `utmpx.h` (XPG4.2): XPG User Accounting Database Functions.

`struct utsname`

  `sys/utsname.h` (POSIX.1): Platform Type Identification.

`type va_arg (va_list ap, type)`

  `stdarg.h` (ISO): Argument Access Macros.

`void va_copy (va_list dest, va_list src)`

  `stdarg.h` (C99): Argument Access Macros.

`void va_end (va_list ap)`

  `stdarg.h` (ISO): Argument Access Macros.

`va_list`

  `stdarg.h` (ISO): Argument Access Macros.

`void va_start (va_list ap, last-required)`

  `stdarg.h` (ISO): Argument Access Macros.

`void * valloc (size_t size)`

  `malloc.h` (BSD): Allocating Aligned Memory Blocks.

  `stdlib.h` (BSD): Allocating Aligned Memory Blocks.

`int vasprintf (char **ptr, const char *template, va_list ap)`

  `stdio.h` (GNU): Variable Arguments Output Functions.

`int vdprintf (int fd, const char *template, va_list ap)`

  `stdio.h` (POSIX): Variable Arguments Output Functions.

`void verr (int status, const char *format, va_list ap)`

  `err.h` (BSD): Error Messages.

`void verrx (int status, const char *format, va_list ap)`

  `err.h` (BSD): Error Messages.

`int versionsort (const struct dirent **a, const struct dirent **b)`

  `dirent.h` (GNU): Scanning the Content of a Directory.

`int versionsort64 (const struct dirent64 **a, const struct dirent64 **b)`

  `dirent.h` (GNU): Scanning the Content of a Directory.

`pid_t vfork (void)`

  `unistd.h` (BSD): Creating a Process.

`int vfprintf (FILE *stream, const char *template, va_list ap)`

  `stdio.h` (ISO): Variable Arguments Output Functions.

`int vfscanf (FILE *stream, const char *template, va_list ap)`

  `stdio.h` (ISO): Variable Arguments Input Functions.

`int vfwprintf (FILE *stream, const wchar_t *template, va_list ap)`

  `wchar.h` (ISO): Variable Arguments Output Functions.

`int vfwscanf (FILE *stream, const wchar_t *template, va_list ap)`

  `wchar.h` (ISO): Variable Arguments Input Functions.

`int vlimit (int resource, int limit)`

  `sys/vlimit.h` (BSD): Limiting Resource Usage.

`int vprintf (const char *template, va_list ap)`

  `stdio.h` (ISO): Variable Arguments Output Functions.

`int vscanf (const char *template, va_list ap)`

  `stdio.h` (ISO): Variable Arguments Input Functions.

`int vsnprintf (char *s, size_t size, const char *template, va_list ap)`

  `stdio.h` (GNU): Variable Arguments Output Functions.

`int vsprintf (char *s, const char *template, va_list ap)`

  `stdio.h` (ISO): Variable Arguments Output Functions.

`int vsscanf (const char *s, const char *template, va_list ap)`

  `stdio.h` (ISO): Variable Arguments Input Functions.

`int vswprintf (wchar_t *ws, size_t size, const wchar_t *template, va_list ap)`

  `wchar.h` (GNU): Variable Arguments Output Functions.

`int vswscanf (const wchar_t *s, const wchar_t *template, va_list ap)`

  `wchar.h` (ISO): Variable Arguments Input Functions.

`void vsyslog (int facility_priority, const char *format, va_list arglist)`

  `syslog.h` (BSD): syslog, vsyslog.

`void vwarn (const char *format, va_list ap)`

  `err.h` (BSD): Error Messages.

`void vwarnx (const char *format, va_list ap)`

  `err.h` (BSD): Error Messages.

`int vwprintf (const wchar_t *template, va_list ap)`

  `wchar.h` (ISO): Variable Arguments Output Functions.

`int vwscanf (const wchar_t *template, va_list ap)`

  `wchar.h` (ISO): Variable Arguments Input Functions.

`pid_t wait (int *status-ptr)`

  `sys/wait.h` (POSIX.1): Process Completion.

`pid_t wait3 (int *status-ptr, int options, struct rusage *usage)`

  `sys/wait.h` (BSD): BSD Process Wait Function.

`pid_t wait4 (pid_t pid, int *status-ptr, int options, struct rusage *usage)`

  `sys/wait.h` (BSD): Process Completion.

`pid_t waitpid (pid_t pid, int *status-ptr, int options)`

  `sys/wait.h` (POSIX.1): Process Completion.

`void warn (const char *format, …)`

  `err.h` (BSD): Error Messages.

`void warnx (const char *format, …)`

  `err.h` (BSD): Error Messages.

`wchar_t`

  `stddef.h` (ISO): Introduction to Extended Characters.

`wchar_t * wcpcpy (wchar_t *restrict wto, const wchar_t *restrict wfrom)`

  `wchar.h` (GNU): Copying Strings and Arrays.

`wchar_t * wcpncpy (wchar_t *restrict wto, const wchar_t *restrict wfrom, size_t size)`

  `wchar.h` (GNU): Truncating Strings while Copying.

`size_t wcrtomb (char *restrict s, wchar_t wc, mbstate_t *restrict ps)`

  `wchar.h` (ISO): Converting Single Characters.

`int wcscasecmp (const wchar_t *ws1, const wchar_t *ws2)`

  `wchar.h` (GNU): String/Array Comparison.

`wchar_t * wcscat (wchar_t *restrict wto, const wchar_t *restrict wfrom)`

  `wchar.h` (ISO): Concatenating Strings.

`wchar_t * wcschr (const wchar_t *wstring, wchar_t wc)`

  `wchar.h` (ISO): Search Functions.

`wchar_t * wcschrnul (const wchar_t *wstring, wchar_t wc)`

  `wchar.h` (GNU): Search Functions.

`int wcscmp (const wchar_t *ws1, const wchar_t *ws2)`

  `wchar.h` (ISO): String/Array Comparison.

`int wcscoll (const wchar_t *ws1, const wchar_t *ws2)`

  `wchar.h` (ISO): Collation Functions.

`wchar_t * wcscpy (wchar_t *restrict wto, const wchar_t *restrict wfrom)`

  `wchar.h` (ISO): Copying Strings and Arrays.

`size_t wcscspn (const wchar_t *wstring, const wchar_t *stopset)`

  `wchar.h` (ISO): Search Functions.

`wchar_t * wcsdup (const wchar_t *ws)`

  `wchar.h` (GNU): Copying Strings and Arrays.

`size_t wcsftime (wchar_t *s, size_t size, const wchar_t *template, const struct tm *brokentime)`

  `time.h` (ISO): Formatting Calendar Time.

`size_t wcslcat (wchar_t *restrict to, const wchar_t *restrict from, size_t size)`

  `string.h` (POSIX.1-2024): Truncating Strings while Copying.

`size_t wcslcpy (wchar_t *restrict to, const wchar_t *restrict from, size_t size)`

  `string.h` (POSIX.1-2024): Truncating Strings while Copying.

`size_t wcslen (const wchar_t *ws)`

  `wchar.h` (ISO): String Length.

`int wcsncasecmp (const wchar_t *ws1, const wchar_t *s2, size_t n)`

  `wchar.h` (GNU): String/Array Comparison.

`wchar_t * wcsncat (wchar_t *restrict wto, const wchar_t *restrict wfrom, size_t size)`

  `wchar.h` (ISO): Truncating Strings while Copying.

`int wcsncmp (const wchar_t *ws1, const wchar_t *ws2, size_t size)`

  `wchar.h` (ISO): String/Array Comparison.

`wchar_t * wcsncpy (wchar_t *restrict wto, const wchar_t *restrict wfrom, size_t size)`

  `wchar.h` (ISO): Truncating Strings while Copying.

`size_t wcsnlen (const wchar_t *ws, size_t maxlen)`

  `wchar.h` (GNU): String Length.

`size_t wcsnrtombs (char *restrict dst, const wchar_t **restrict src, size_t nwc, size_t len, mbstate_t *restrict ps)`

  `wchar.h` (GNU): Converting Multibyte and Wide Character Strings.

`wchar_t * wcspbrk (const wchar_t *wstring, const wchar_t *stopset)`

  `wchar.h` (ISO): Search Functions.

`wchar_t * wcsrchr (const wchar_t *wstring, wchar_t wc)`

  `wchar.h` (ISO): Search Functions.

`size_t wcsrtombs (char *restrict dst, const wchar_t **restrict src, size_t len, mbstate_t *restrict ps)`

  `wchar.h` (ISO): Converting Multibyte and Wide Character Strings.

`size_t wcsspn (const wchar_t *wstring, const wchar_t *skipset)`

  `wchar.h` (ISO): Search Functions.

`wchar_t * wcsstr (const wchar_t *haystack, const wchar_t *needle)`

  `wchar.h` (ISO): Search Functions.

`double wcstod (const wchar_t *restrict string, wchar_t **restrict tailptr)`

  `wchar.h` (ISO): Parsing of Floats.

`float wcstof (const wchar_t *string, wchar_t **tailptr)`

  `wchar.h` (ISO): Parsing of Floats.

`_FloatN wcstofN (const wchar_t *string, wchar_t **tailptr)`

  `wchar.h` (GNU): Parsing of Floats.

`_FloatNx wcstofNx (const wchar_t *string, wchar_t **tailptr)`

  `wchar.h` (GNU): Parsing of Floats.

`intmax_t wcstoimax (const wchar_t *restrict string, wchar_t **restrict tailptr, int base)`

  `wchar.h` (ISO): Parsing of Integers.

`wchar_t * wcstok (wchar_t *newstring, const wchar_t *delimiters, wchar_t **save_ptr)`

  `wchar.h` (ISO): Finding Tokens in a String.

`long int wcstol (const wchar_t *restrict string, wchar_t **restrict tailptr, int base)`

  `wchar.h` (ISO): Parsing of Integers.

`long double wcstold (const wchar_t *string, wchar_t **tailptr)`

  `wchar.h` (ISO): Parsing of Floats.

`long long int wcstoll (const wchar_t *restrict string, wchar_t **restrict tailptr, int base)`

  `wchar.h` (ISO): Parsing of Integers.

`size_t wcstombs (char *string, const wchar_t *wstring, size_t size)`

  `stdlib.h` (ISO): Non-reentrant Conversion of Strings.

`long long int wcstoq (const wchar_t *restrict string, wchar_t **restrict tailptr, int base)`

  `wchar.h` (GNU): Parsing of Integers.

`unsigned long int wcstoul (const wchar_t *restrict string, wchar_t **restrict tailptr, int base)`

  `wchar.h` (ISO): Parsing of Integers.

`unsigned long long int wcstoull (const wchar_t *restrict string, wchar_t **restrict tailptr, int base)`

  `wchar.h` (ISO): Parsing of Integers.

`uintmax_t wcstoumax (const wchar_t *restrict string, wchar_t **restrict tailptr, int base)`

  `wchar.h` (ISO): Parsing of Integers.

`unsigned long long int wcstouq (const wchar_t *restrict string, wchar_t **restrict tailptr, int base)`

  `wchar.h` (GNU): Parsing of Integers.

`wchar_t * wcswcs (const wchar_t *haystack, const wchar_t *needle)`

  `wchar.h` (XPG): Search Functions.

`size_t wcsxfrm (wchar_t *restrict wto, const wchar_t *wfrom, size_t size)`

  `wchar.h` (ISO): Collation Functions.

`int wctob (wint_t c)`

  `wchar.h` (ISO): Converting Single Characters.

`int wctomb (char *string, wchar_t wchar)`

  `stdlib.h` (ISO): Non-reentrant Conversion of Single Characters.

`wctrans_t wctrans (const char *property)`

  `wctype.h` (ISO): Mapping of wide characters..

`wctrans_t`

  `wctype.h` (ISO): Mapping of wide characters..

`wctype_t wctype (const char *property)`

  `wctype.h` (ISO): Character class determination for wide characters.

`wctype_t`

  `wctype.h` (ISO): Character class determination for wide characters.

`wint_t`

  `wchar.h` (ISO): Introduction to Extended Characters.

`wchar_t * wmemchr (const wchar_t *block, wchar_t wc, size_t size)`

  `wchar.h` (ISO): Search Functions.

`int wmemcmp (const wchar_t *a1, const wchar_t *a2, size_t size)`

  `wchar.h` (ISO): String/Array Comparison.

`wchar_t * wmemcpy (wchar_t *restrict wto, const wchar_t *restrict wfrom, size_t size)`

  `wchar.h` (ISO): Copying Strings and Arrays.

`wchar_t * wmemmove (wchar_t *wto, const wchar_t *wfrom, size_t size)`

  `wchar.h` (ISO): Copying Strings and Arrays.

`wchar_t * wmempcpy (wchar_t *restrict wto, const wchar_t *restrict wfrom, size_t size)`

  `wchar.h` (GNU): Copying Strings and Arrays.

`wchar_t * wmemset (wchar_t *block, wchar_t wc, size_t size)`

  `wchar.h` (ISO): Copying Strings and Arrays.

`int wordexp (const char *words, wordexp_t *word-vector-ptr, int flags)`

  `wordexp.h` (POSIX.2): Calling `wordexp`.

`wordexp_t`

  `wordexp.h` (POSIX.2): Calling `wordexp`.

`void wordfree (wordexp_t *word-vector-ptr)`

  `wordexp.h` (POSIX.2): Calling `wordexp`.

`int wprintf (const wchar_t *template, …)`

  `wchar.h` (ISO): Formatted Output Functions.

`ssize_t write (int filedes, const void *buffer, size_t size)`

  `unistd.h` (POSIX.1): Input and Output Primitives.

`ssize_t writev (int filedes, const struct iovec *vector, int count)`

  `sys/uio.h` (BSD): Fast Scatter-Gather I/O.

`int wscanf (const wchar_t *template, …)`

  `wchar.h` (ISO): Formatted Input Functions.

`double y0 (double x)`

  `math.h` (SVID): Special Functions.

`float y0f (float x)`

  `math.h` (SVID): Special Functions.

`_FloatN y0fN (_FloatN x)`

  `math.h` (GNU): Special Functions.

`_FloatNx y0fNx (_FloatNx x)`

  `math.h` (GNU): Special Functions.

`long double y0l (long double x)`

  `math.h` (SVID): Special Functions.

`double y1 (double x)`

  `math.h` (SVID): Special Functions.

`float y1f (float x)`

  `math.h` (SVID): Special Functions.

`_FloatN y1fN (_FloatN x)`

  `math.h` (GNU): Special Functions.

`_FloatNx y1fNx (_FloatNx x)`

  `math.h` (GNU): Special Functions.

`long double y1l (long double x)`

  `math.h` (SVID): Special Functions.

`double yn (int n, double x)`

  `math.h` (SVID): Special Functions.

`float ynf (int n, float x)`

  `math.h` (SVID): Special Functions.

`_FloatN ynfN (int n, _FloatN x)`

  `math.h` (GNU): Special Functions.

`_FloatNx ynfNx (int n, _FloatNx x)`

  `math.h` (GNU): Special Functions.

`long double ynl (int n, long double x)`

  `math.h` (SVID): Special Functions.