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semaphore.h(0P)            POSIX Programmer's Manual           semaphore.h(0P)
PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the  corresponding
       Linux  manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.
NAME
       semaphore.h -- semaphores
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  <semaphore.h> header shall define the symbolic constant SEM_FAILED
       which shall have type sem_t *.
       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 <fcntl.h> and <time.h> headers.
       The following sections are informative.
APPLICATION USAGE
       None.
RATIONALE
       None.
FUTURE DIRECTIONS
       None.
SEE ALSO
       <fcntl.h>, <sys_types.h>, <time.h>
       The   System   Interfaces   volume   of   POSIX.1-2008,    sem_close(),
       sem_destroy(),   sem_getvalue(),  sem_init(),  sem_open(),  sem_post(),
       sem_timedwait(), sem_trywait(), sem_unlink()
COPYRIGHT
       Portions of this text are reprinted and reproduced in  electronic  form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri-
       cal and Electronics Engineers,  Inc  and  The  Open  Group.   (This  is
       POSIX.1-2008  with  the  2013  Technical Corrigendum 1 applied.) 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.unix.org/online.html .
       Any  typographical  or  formatting  errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files  to  man page format. To report such errors, see https://www.ker-
       nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group                  2013                      semaphore.h(0P)