Name
semctl
Synopsis
semctl id, semnum, cmd, arg
Description
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.
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