table of contents
SEM_POST(3) | Linux Programmer's Manual | SEM_POST(3) |
NAME¶
sem_post - unlock a semaphore
SYNOPSIS¶
#include <semaphore.h> int sem_post(sem_t *sem);
Link with -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¶
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¶
COLOPHON¶
This page is part of release 3.53 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/.
2012-05-13 | Linux |