<semaphore.h>(P)					     POSIX Programmer's Manual						  <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 performing 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 .

IEEE
/The Open Group						       2003							  <semaphore.h>(P)