Unix/Linux Go Back    


Linux 2.6 - man page for sem_getvalue (linux section 3posix)

Linux & Unix Commands - Search Man Pages
Man Page or Keyword Search:   man
Select Man Page Set:       apropos Keyword Search (sections above)


SEM_GETVALUE(P) 		    POSIX Programmer's Manual			  SEM_GETVALUE(P)

NAME
       sem_getvalue - get the value of a semaphore (REALTIME)

SYNOPSIS
       #include <semaphore.h>

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

DESCRIPTION
       The  sem_getvalue()  function shall update 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 object to which sval points shall either be set to zero or to a
       negative number whose absolute value represents the number of processes	waiting  for  the
       semaphore at some unspecified time during the call.

RETURN VALUE
       Upon successful completion, the sem_getvalue() function shall return a value of zero. Oth-
       erwise, it shall return a value of -1 and set errno to indicate the error.

ERRORS
       The sem_getvalue() function shall fail if:

       EINVAL The sem argument does not refer to a valid semaphore.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       The sem_getvalue() function is part of the Semaphores option and need not be available  on
       all implementations.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       semctl()  , semget() , semop() , sem_post() , sem_timedwait() , sem_trywait() , sem_wait()
       , the Base Definitions volume of IEEE Std 1003.1-2001, <semaphore.h>

COPYRIGHT
       Portions of this text are reprinted and	reproduced  in	electronic  form  from	IEEE  Std
       1003.1,	2003  Edition,	Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003  by
       the  Institute  of  Electrical  and  Electronics Engineers, Inc and The Open Group. In the
       event of any discrepancy between this version and the original IEEE  and  The  Open  Group
       Standard, the original IEEE and The Open Group Standard is the referee document. The orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group			       2003				  SEM_GETVALUE(P)
Unix & Linux Commands & Man Pages : ©2000 - 2018 Unix and Linux Forums


All times are GMT -4. The time now is 09:55 PM.