Manual Pages for UNIX Operating System command usage for man sem_getvalue

Standard C Library Functions                     sem_getvalue(3C)



NAME
     sem_getvalue - get the value of a semaphore

SYNOPSIS
     #include 

     int sem_getvalue(sem_t *restrict sem, int *restrict sval);


DESCRIPTION
     The sem_getvalue() function updates the location  referenced
     by  the  sval  argument  to  have the value of the semaphore
     referenced by sem without affecting the state of  the  sema-
     phore.  The  updated  value  represents  an actual semaphore
     value that occurred at  some  unspecified  time  during  the
     call,  but  it need not be the actual value of the semaphore
     when it is returned to the calling process.


     If sem is locked, then the value returned by  sem_getvalue()
     is  either  zero  or  a negative number whose absolute value
     represents the number of processes waiting for the semaphore
     at some unspecified time during the call.


     The value set in sval may be 0 or positive. If  sval  is  0,
     there  may  be  other processes (or LWPs or threads) waiting
     for the semaphore; if sval is positive, no process is  wait-
     ing.

RETURN VALUES
     Upon successful completion, sem_getvalue() returns 0. Other-
     wise, it returns -1 and sets errno to indicate the error.

ERRORS
     The  sem_getvalue() function will fail if:

     EINVAL     The sem argument does not refer to a valid  sema-
                phore.


     ENOSYS     The sem_getvalue() function is not  supported  by
                the system.


ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:







SunOS 5.11           Last change: 5 Feb 2008                    1






Standard C Library Functions                     sem_getvalue(3C)



     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Interface Stability         | Committed                   |
    |_____________________________|_____________________________|
    | MT-Level                    | MT-Safe                     |
    |_____________________________|_____________________________|
    | Standard                    | See standards(5).           |
    |_____________________________|_____________________________|


SEE ALSO
     semctl(2), semget(2), semop(2), sem_post(3C),  sem_wait(3C),
     attributes(5), standards(5)









































SunOS 5.11           Last change: 5 Feb 2008                    2