Manual:

Reference:

-- Perl 5.8.7 documentation --

msgctl

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 which 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, IPC::SysV, and IPC::Semaphore documentation.