Man Page

Manual Section... (3) - page: sem_post

 

NAME

sem_post - unlock a semaphore  

SYNOPSIS

#include <semaphore.h>

int sem_post(sem_t *sem);

Link with -lrt or -pthread.  

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
sem is not a valid semaphore.
EOVERFLOW
The maximum allowable value for a semaphore would be exceeded.
 

CONFORMING TO

POSIX.1-2001.  

NOTES

sem_post() is async-signal-safe: it may be safely called within a signal handler.  

EXAMPLE

See sem_wait(3).  

SEE ALSO

sem_getvalue(3), sem_wait(3), sem_overview(7)  

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/.


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
CONFORMING TO
NOTES
EXAMPLE
SEE ALSO
COLOPHON

This document was created by man2html, using the manual pages.
Time: 15:26:50 GMT, June 11, 2010

Leave a Reply

You must be logged in to post a comment.