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# semctl

Perl 5 version 26.0 documentation
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# semctl

Perl functions A-Z | Perl functions by category | The 'perlfunc' manpage

- semctl ID,SEMNUM,CMD,ARG

  Calls the System V IPC function semctl(2). You'll probably have to say

          use IPC::SysV;

  first to get the correct constant definitions. If CMD is IPC_STAT or GETALL, then ARG must be a variable that will hold the returned semid_ds structure or semaphore value array. Returns like ioctl: the undefined value for error, "`0 but true`" for zero, or the actual return value otherwise. The ARG must consist of a vector of native short integers, which may be created with `pack("s!",(0)x$nsem)`. See also SysV IPC in perlipc and the documentation for IPC::SysV and IPC::Semaphore .

  Portability issues: semctl in perlport.