Perl 5 version 26.3 documentation


  • semctl ID,SEMNUM,CMD,ARG

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

    1. 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.