Perl 5 version 26.3 documentation


  • 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. my $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 and the documentation for IPC::SysV and IPC::Semaphore .

    Portability issues: semop in perlport.