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UNIX for Dummies Questions & Answers
what's the difference between signal and semaphore?
Post 302524089 by stackpop on Saturday 21st of May 2011 11:30:56 AM
05-21-2011
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LEARN ABOUT DEBIAN
sem_post
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
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 3.44 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/. Linux 2012-05-13 SEM_POST(3)