This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

       None.

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for  Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       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.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                                   2017                                   semaphore.h(7POSIX)

       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 <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.

       Thefollowingsectionsareinformative.

       None.

       semaphore.h — semaphores

       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.

       None.

<fcntl.h>, <sys_types.h>, <time.h>

       The System Interfaces volume of POSIX.1‐2017,  sem_close(),  sem_destroy(),  sem_getvalue(),  sem_init(),
       sem_open(), sem_post(), sem_timedwait(), sem_trywait(), sem_unlink()

       #include <semaphore.h>