=over

=item 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 C<IPC_STAT>,
then ARG must be a variable which will hold the returned C<msqid_ds>
structure.  Returns like C<ioctl()>: the undefined value for error, "C<0> but
true" for zero, or the actual return value otherwise.  See also
C<IPC::SysV> and C<IPC::Semaphore::Msg> documentation.

=back