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# semop

Perl 5 version 18.2 documentation
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# semop

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

- semop KEY,OPSTRING

  Calls the System V IPC function semop(2) for semaphore operations such as signalling and waiting. OPSTRING must be a packed array of semop structures. Each semop structure can be generated with `pack("s!3", $semnum, $semop, $semflag)` . The length of OPSTRING implies the number of semaphore operations. Returns true if successful, false on error. As an example, the following code waits on semaphore $semnum of semaphore id $semid:

          $semop = pack("s!3", $semnum, -1, 0);    die "Semaphore trouble: $!\n" unless semop($semid, $semop);

  To signal the semaphore, replace `-1` with `1` . See also SysV IPC in perlipc, `IPC::SysV` , and `IPC::SysV::Semaphore` documentation.

  Portability issues: semop in perlport.