semaphore.h

<semaphore.h>(P)					     <semaphore.h>(P)



NAME
       semaphore.h - semaphores (REALTIME)

SYNOPSIS
       #include <semaphore.h>

DESCRIPTION
       The <semaphore.h> header shall define the sem_t type, used in perform-
       ing semaphore operations. The semaphore may  be	implemented  using  a
       file  descriptor,  in  which  case applications are able to open up at
       least  a	 total	of  {OPEN_MAX}	files  and  semaphores.	 The   symbol
       SEM_FAILED shall be defined (see sem_open()).

       The  following  shall be declared as functions and may also be defined
       as macros. Function prototypes shall be provided.


	      int    sem_close(sem_t *);
	      int    sem_destroy(sem_t *);
	      int    sem_getvalue(sem_t *restrict, int *restrict);
	      int    sem_init(sem_t *, int, unsigned);
	      sem_t *sem_open(const char *, int, ...);
	      int    sem_post(sem_t *);

	      int    sem_timedwait(sem_t *restrict, const struct timespec *restrict);

	      int    sem_trywait(sem_t *);
	      int    sem_unlink(const char *);
	      int    sem_wait(sem_t *);

       Inclusion of the <semaphore.h> header may make visible symbols defined
       in the headers <fcntl.h> and <sys/types.h>.

       The following sections are informative.

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       <fcntl.h>   ,   <sys/types.h>   ,  the  System  Interfaces  volume  of
       IEEE Std 1003.1-2001,   sem_destroy(),	sem_getvalue(),	  sem_init(),
       sem_open(),  sem_post(), sem_timedwait(), sem_trywait(), sem_unlink(),
       sem_wait()

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic	 form
       from  IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- 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  original  Standard  can be
       obtained online at http://www.opengroup.org/unix/online.html .



POSIX				     2003		     <semaphore.h>(P)