Name
sem_post — unlock a semaphore
Synopsis
#include <semaphore.h>
int sem_post( |
sem_t *sem); |
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DESCRIPTION
sem_post() increments
(unlocks) the semaphore pointed to by sem. If the semaphore's value
consequently becomes greater than zero, then another process
or thread blocked in a sem_wait(3) call will be
woken up and proceed to lock the semaphore.
RETURN VALUE
sem_post() returns 0 on
success; on error, the value of the semaphore is left
unchanged, −1 is returned, and errno is set to indicate the error.
ERRORS
- EINVAL
-
semis not a valid semaphore. - EOVERFLOW
-
The maximum allowable value for a semaphore would be exceeded.
COLOPHON
This page is part of release 3.24 of the Linux man-pages project. A
description of the project, and information about reporting
bugs, can be found at
http://www.kernel.org/doc/man-pages/.
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t Copyright (C) 2006 Michael Kerrisk <mtk.manpagesgmail.com> Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Since the Linux kernel and libraries are constantly changing, this manual page may be incorrect or out-of-date. The author(s) assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. The author(s) may not have taken the same level of care in the production of this manual, which is licensed free of charge, as they might when working professionally. Formatted or processed versions of this manual, if unaccompanied by the source, must acknowledge the copyright and authors of this work. |