=over =item msgctl ID,CMD,ARG X<msgctl> Calls the System V IPC function L<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 that will hold the returned C<msqid_ds> structure. Returns like L<C<ioctl>|/ioctl FILEHANDLE,FUNCTION,SCALAR>: the undefined value for error, C<"0 but true"> for zero, or the actual return value otherwise. See also L<perlipc/"SysV IPC"> and the documentation for L<C<IPC::SysV>|IPC::SysV> and L<C<IPC::Semaphore>|IPC::Semaphore>. Portability issues: L<perlport/msgctl>. =back