semctl
semctl id, semnum, cmd, arg
Calls the System V IPC system call semctl(2)
. 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. 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.
3.15.14.98