=over =item semctl ID,SEMNUM,CMD,ARG X Calls the System V IPC function semctl(2). You'll probably have to say use IPC::SysV; first to get the correct constant definitions. If CMD is IPC_STAT or GETALL, then ARG must be a variable that will hold the returned semid_ds structure or semaphore value array. Returns like C: the undefined value for error, "C<0 but true>" for zero, or the actual return value otherwise. The ARG must consist of a vector of native short integers, which may be created with C. See also L, C, C documentation. =back