-- Perl 5.8.7 documentation --
semctl
  • semctl ID,SEMNUM,CMD,ARG

    Calls the System V IPC function semctl. 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 which 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, IPC::SysV, IPC::Semaphore documentation.