NAME

semctl - SysV semaphore control operations


SYNOPSIS

semctl ID,SEMNUM,CMD,ARG


DESCRIPTION

Calls the System V IPC function semctl. If CMD is &IPC_STAT or &GETALL, then ARG must be a variable which will hold the returned semid_ds structure or semaphore value array. Returns like ioctl: the undefined value for error, ``0 but true'' for zero, or the actual return value otherwise.