<semaphore.h>(0P)                                   POSIX Programmer's Manual                                  <semaphore.h>(0P)



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, Copy-
       right (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.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                             <semaphore.h>(0P)