sem_getvalue(3C)					      sem_getvalue(3C)

NAME    [Toc]    [Back]

     sem_getvalue - get	the value of a posix named or unnamed semaphore

SYNOPSIS    [Toc]    [Back]

     #include <semaphore.h>

     int sem_getvalue(sem_t *sem<b>, int *value<b>);

DESCRIPTION    [Toc]    [Back]

     sem_getvalue obtains the current value of the semaphore located at
     address sem, and stores it	at address value. The returned value should be
     viewed as a snapshot only,	useful for debugging.

     If	the number stored at value is positive,	then the semaphore is
     available.	 If the	number stored at value is zero,	then the semaphore is
     not available.  If	the number stored at value is negative,	then the
     semaphore is not available	and the	absolute value of the number
     represents	the number of processes	currently blocked on the semaphore.

     The address sem may reside	anywhere in the	calling	processes address
     space, but	the process must have read and write access to sem.

     sem_getvalue will fail if the following is	true:

     [EINVAL]	 The semaphore located at address sem is not a valid posix
		 named or unnamed semaphore.

SEE ALSO    [Toc]    [Back]

     sem_init(3C), sem_destroy(3C), sem_getvalue(3C), sem_post(3C),
     sem_wait(3C), sem_trywait(3C), sem_open(3C), sem_close(3C),
     sem_unlink(3C),

DIAGNOSTICS    [Toc]    [Back]

     Upon successful completion, a value of 0 is returned to the calling
     process. Otherwise, a value of -1 is returned and errno is	set to
     indicate the error.


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