3.2.93 msgctl

msgctl ID, CMD, ARG

This function calls the msgctl(2) system call. See msgctl(2) for details. If CMD is &IPC_STAT, then ARG must be a variable that will hold the returned msqid_ds structure. The return value works like ioctl's: the undefined value for error, "0 but true" for zero, or the actual return value otherwise. On error, it puts the error code into $!. Before calling, you should say:

require "ipc.ph";
require "msg.ph";

This function is available only on machines supporting System V IPC, which turns out to be far fewer than those supporting sockets.