June 2002
Beginner
759 pages
80h 42m
English
semctl
semctl id, semnum, cmd, arg
Calls the System V IPC system call semctl(2). If
cmd is &IPC_STAT or &GETALL, then
argmust be a variable which will hold
the returned semid_ds structure
or semaphore value array. The function returns like ioctl: the undefined value for error,
0 but true for zero, or the
actual return value otherwise. On error, it puts the error code
into $!. Before calling, you
should say:
require "ipc.ph"; require "sem.ph";
This function is available only on machines supporting System V IPC.