code = %semctl(sem-ID, semnum, cmd, arg)

sem-ID

Semaphore ID returned by a call to %semget().

semnum

Semaphore number in the set, when applicable (depending on cmd).

cmd

Valid values for cmd are defined in sem.h and ipc.h. The commands below are executed with respect to the semaphore specified by sem-ID and semnum:

getval

Returns the value of semval.

setval

Sets semval to the value of arg.

getpid

Returns the value of sempid.

getncnt

Returns the value of semncnt.

getzcnt

Returns the value of semzcnt.

The commands below apply to all semaphores in the set:

getall

Place all the semaphore values in the arg dimensioned array.

setall

Set all the semaphores to the values contained in the dimensioned array arg.

These commands are also available:

ipc$stat

Return a dimensioned array that contains the various fields of the UNIX semaphore structures. The elements are (see the UNIX system documentation):

1 sem_perm.uid

2 sem_perm.cid

3 sem_perm.guid

4 sem_perm.gcid

5 sem_perm.mode

6 sem_perm.seq

7 sem_perm.key

8 sem_nsems

9 sem_otime

10 sem_ctime

ipc$set

Sets the values of the below members of the data structure associated to sem-ID to the first three elements of the array arg:

1 sem_perm.uid

2 sem_perm.gid

3 sem_perm.mode

ipc$rmid

Removes the semaphore identifier.

arg

Dimensioned array that contains the argument.

include dm,bp,unix.h ipc.h

include dm,bp,unix.h sem.h

* Set initial semaphore values

dim val(3)

mat val=0

%semctl(sem-ID, 0, setall, val)