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 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
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

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