msgctl(2) - perldoc - phpman

    msgctl ID,CMD,ARG
            Calls the System V IPC function msgctl(2). You'll probably have
            to say

                use IPC::SysV;

            first to get the correct constant definitions. If CMD is
            "IPC_STAT", then ARG must be a variable that will hold the
            returned "msqid_ds" structure. Returns like "ioctl": the
            undefined value for error, "0 but true" for zero, or the actual
            return value otherwise. See also "SysV IPC" in perlipc and the
            documentation for "IPC::SysV" and "IPC::Semaphore".

            Portability issues: "msgctl" in perlport.