Perl 5 version 22.4 documentation

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:

    1.     $semop = pack("s!3", $semnum, -1, 0);
    2.     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.