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Linux 2.6 - man page for sem_post (linux section 3)

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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 3.55 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)
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