msem_unlock(3)						     Library Functions Manual						    msem_unlock(3)

NAME

       msem_unlock - Unlocks a semaphore

LIBRARY

       Standard C Library (libc.a)

SYNOPSIS

       #include <sys/mman.h>
       int msem_unlock (      msemaphore *sem,	    int condition );

PARAMETERS

       Points  to an msemaphore structure which specifies the semaphore to be unlocked.  Determines whether the msem_unlock() function unlocks the
       semaphore if no other processes are waiting to lock it.

DESCRIPTION

       The msem_unlock() function unlocks a binary semaphore.

       If the condition parameter is 0 (zero), the semaphore is unlocked, whether or not any other processes are currently attempting to lock  it.
       If  the	condition  parameter  is MSEM_IF_WAITERS, and another process is waiting to lock the semaphore or it cannot be reliably determined
       whether some process is waiting to lock the semaphore, the semaphore is unlocked by the calling process.  If  the  condition  parameter	is
       MSEM_IF_WAITERS, and no process is waiting to lock the semaphore, the semaphore will not be unlocked and an error will be returned.

       All calls to the msem_lock() and msem_unlock() functions by multiple processes sharing a common msemaphore structure behave as if the calls
       were serialized.

       If the msemaphore structure contains any value not resulting from a call to  the  msem_init()  function	followed  by  a  (possibly  empty)
       sequence of calls to the msem_lock() and msem_unlock() functions, the results are undefined.  The address of an msemaphore structure may be
       significant.  If the msemaphore structure contains any value copied from an msemaphore structure at a  different  address,  the	result	is
       undefined.

NOTES

       Trial use

RETURN VALUES

       On  successful  completion, the msem_unlock() function returns 0 (zero).  On error, the msem_unlock() function returns -1 and sets errno to
       indicate the error.

ERRORS

       If the msem_unlock() function fails, errno may be set to one of the following values: MSEM_IF_WAITERS was specified and there were no wait-
       ers.  The sem parameter points to an msemaphore structure which specifies a semaphore which has been removed, or the condition parameter is
       invalid.

RELATED INFORMATION

       Functions: msem_init(3), msem_lock(3), msem_remove(3) delim off

																    msem_unlock(3)