=over =item msgctl ID,CMD,ARG X Calls the System V IPC function L. You'll probably have to say use IPC::SysV; first to get the correct constant definitions. If CMD is C, then ARG must be a variable that will hold the returned C structure. Returns like L|/ioctl FILEHANDLE,FUNCTION,SCALAR>: the undefined value for error, C<"0 but true"> for zero, or the actual return value otherwise. See also L and the documentation for L|IPC::SysV> and L|IPC::Semaphore>. Portability issues: L. =back