=over =item shmctl ID,CMD,ARG X<shmctl> Calls the System V IPC function shmctl. 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<shmid_ds> structure. Returns like ioctl: L<C<undef>|/undef EXPR> for error; "C<0> but true" for zero; and the actual return value otherwise. See also L<perlipc/"SysV IPC"> and the documentation for L<C<IPC::SysV>|IPC::SysV>. Portability issues: L<perlport/shmctl>. =back