termios.h(7POSIX)

PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME
termios.h — define values for termios

SYNOPSIS

#include <termios.h>

DESCRIPTION
The <termios.h> header shall contain the definitions used by the terminal I/O interfaces (see Chapter 11, General Terminal Interface for the structures and names defined).

  The termios Structure

The <termios.h> header shall define the following data types through typedef:

cc_t
    Used for terminal special characters.

speed_t
    Used for terminal baud rates.

tcflag_t
    Used for terminal modes.

The above types shall be all unsigned integer types.

The implementation shall support one or more programming environments in which the widths of cc_t, speed_t, and tcflag_t are no greater than the width of type long. The names of these programming environments can be obtained using the confstr() function or the getconf utility.

The <termios.h> header shall define the termios structure, which shall include at least the following members:

    tcflag_t  c_iflag     Input modes.
    tcflag_t  c_oflag     Output modes.
    tcflag_t  c_cflag     Control modes.
    tcflag_t  c_lflag     Local modes.
    cc_t      c_cc[NCCS]  Control characters.

The <termios.h> header shall define the following symbolic constant:

NCCS
    Size of the array c_cc for control characters.

The <termios.h> header shall define the following symbolic constants for use as subscripts for the array c_cc:
Subscript Usage
Canonical Mode | Non-Canonical Mode | Description
VEOF |  | EOF character.
VEOL |  | EOL character.
VERASE |  | ERASE character.
VINTR | VINTR | INTR character.
VKILL |  | KILL character.
 | VMIN | MIN value.
VQUIT | VQUIT | QUIT character.
VSTART | VSTART | START character.
VSTOP | VSTOP | STOP character.
VSUSP | VSUSP | SUSP character.
 | VTIME | TIME value.

The subscript values shall be suitable for use in #if preprocessing directives and shall be distinct, except that the VMIN and VTIME subscripts may have the same values as the VEOF and VEOL subscripts, respectively.

  Input Modes

The <termios.h> header shall define the following symbolic constants for use as flags in the c_iflag field. The c_iflag field describes the basic terminal input control.

BRKINT
    Signal interrupt on break.

ICRNL
    Map CR to NL on input.

IGNBRK
    Ignore break condition.

IGNCR
    Ignore CR.

IGNPAR
    Ignore characters with parity errors.

INLCR
    Map NL to CR on input.

INPCK
    Enable input parity check.

ISTRIP
    Strip character.

IXANY
    Enable any character to restart output.

IXOFF
    Enable start/stop input control.

IXON
    Enable start/stop output control.

PARMRK
    Mark parity errors.

  Output Modes

The <termios.h> header shall define the following symbolic constants for use as flags in the c_oflag field. The c_oflag field specifies the system treatment of output.

OPOST
    Post-process output.

ONLCR
    Map NL to CR-NL on output.

OCRNL
    Map CR to NL on output.

ONOCR
    No CR output at column 0.

ONLRET
    NL performs CR function.

OFDEL
    Fill is DEL.

OFILL
    Use fill characters for delay.

NLDLY
    Select newline delays:

    NL0 Newline type 0.

    NL1 Newline type 1.

CRDLY
    Select carriage-return delays:

    CR0 Carriage-return delay type 0.

    CR1 Carriage-return delay type 1.

    CR2 Carriage-return delay type 2.

    CR3 Carriage-return delay type 3.

TABDLY
    Select horizontal-tab delays:

    TAB0
        Horizontal-tab delay type 0.

    TAB1
        Horizontal-tab delay type 1.

    TAB2
        Horizontal-tab delay type 2.

    TAB3
        Expand tabs to spaces.

BSDLY
    Select backspace delays:

    BS0 Backspace-delay type 0.

    BS1 Backspace-delay type 1.

VTDLY
    Select vertical-tab delays:

    VT0 Vertical-tab delay type 0.

    VT1 Vertical-tab delay type 1.

FFDLY
    Select form-feed delays:

    FF0 Form-feed delay type 0.

    FF1 Form-feed delay type 1.

  Baud Rate Selection

The <termios.h> header shall define the following symbolic constants for use as values of objects of type speed_t.

The input and output baud rates are stored in the termios structure. These are the valid values for objects of type speed_t. Not all baud rates need be supported by the underlying hardware.

B0  Hang up

B50 50 baud

B75 75 baud

B110
    110 baud

B134
    134.5 baud

B150
    150 baud

B200
    200 baud

B300
    300 baud

B600
    600 baud

B1200
    1200 baud

B1800
    1800 baud

B2400
    2400 baud

B4800
    4800 baud

B9600
    9600 baud

B19200
    19200 baud

B38400
    38400 baud

  Control Modes

The <termios.h> header shall define the following symbolic constants for use as flags in the c_cflag field. The c_cflag field describes the hardware control of the terminal; not all values specified are required to be supported by the underlying hardware.

CSIZE
    Character size:

    CS5 5 bits

    CS6 6 bits

    CS7 7 bits

    CS8 8 bits

CSTOPB
    Send two stop bits, else one.

CREAD
    Enable receiver.

PARENB
    Parity enable.

PARODD
    Odd parity, else even.

HUPCL
    Hang up on last close.

CLOCAL
    Ignore modem status lines.

The implementation shall support the functionality associated with the symbols CS7, CS8, CSTOPB, PARODD, and PARENB.

  Local Modes

The <termios.h> header shall define the following symbolic constants for use as flags in the c_lflag field. The c_lflag field of the argument structure is used to control various terminal functions.

ECHO
    Enable echo.

ECHOE
    Echo erase character as error-correcting backspace.

ECHOK
    Echo KILL.

ECHONL
    Echo NL.

ICANON
    Canonical input (erase and kill processing).

IEXTEN
    Enable extended input character processing.

ISIG
    Enable signals.

NOFLSH
    Disable flush after interrupt or quit.

TOSTOP
    Send SIGTTOU for background output.

  Attribute Selection

The <termios.h> header shall define the following symbolic constants for use with tcsetattr():

TCSANOW
    Change attributes immediately.

TCSADRAIN
    Change attributes when output has drained.

TCSAFLUSH
    Change attributes when output has drained; also flush pending input.

  Line Control

The <termios.h> header shall define the following symbolic constants for use with tcflush():

TCIFLUSH
    Flush pending input.

TCIOFLUSH
    Flush both pending input and untransmitted output.

TCOFLUSH
    Flush untransmitted output.

The <termios.h> header shall define the following symbolic constants for use with tcflow():

TCIOFF
    Transmit a STOP character, intended to suspend input data.

TCION
    Transmit a START character, intended to restart input data.

TCOOFF
    Suspend output.

TCOON
    Restart output.

The <termios.h> header shall define the pid_t type as described in <sys/types.h>.

The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.

    speed_t cfgetispeed(const struct termios *);
    speed_t cfgetospeed(const struct termios *);
    int     cfsetispeed(struct termios *, speed_t);
    int     cfsetospeed(struct termios *, speed_t);
    int     tcdrain(int);
    int     tcflow(int, int);
    int     tcflush(int, int);
    int     tcgetattr(int, struct termios *);
    pid_t   tcgetsid(int);
    int     tcsendbreak(int, int);
    int     tcsetattr(int, int, const struct termios *);

The following sections are informative.

APPLICATION USAGE
The following names are reserved for XSI-conformant systems to use as an extension to the above; therefore strictly conforming applications shall not use them:
CBAUD | EXTB | VDSUSP
DEFECHO | FLUSHO | VLNEXT
ECHOCTL | LOBLK | VREPRINT
ECHOKE | PENDIN | VSTATUS
ECHOPRT | SWTCH | VWERASE
EXTA | VDISCARD

RATIONALE
None.

FUTURE DIRECTIONS
None.

SEE ALSO
<sys_types.h>

The System Interfaces volume of POSIX.1-2017, cfgetispeed(), cfgetospeed(), cfsetispeed(), cfsetospeed(), confstr(), tcdrain(), tcflow(), tcflush(), tcgetattr(), tcgetsid(), tcsendbreak(), tcsetattr()

The Shell and Utilities volume of POSIX.1-2017, Chapter 11, General Terminal Interface, getconf

COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .