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msem_unlock(3)
NAME
  msem_unlock - Unlock a semaphore

SYNOPSIS
  #include <sys/mman.h>

  int msem_unlock(
	  msemaphore *sem,
	  int condition );

LIBRARY
  Standard C Library (libc)

PARAMETERS
  sem Points to an msemaphore structure which specifies the semaphore to be
      unlocked.

  condition
      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
  AES Support Level:
      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:

  [EAGAIN]
      MSEM_IF_WAITERS was specified and there were no waiters.

  [EINVAL]
      The sem parameter points to an msemaphore structure which specifies a
      semaphore which has been removed, or the condition parameter is
      invalid.

SEE ALSO
  Functions: msem_init(3), msem_lock(3), msem_remove(3)

Index for Section 3

Alphabetical listing for M

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