Manpages - sem_close.3p

This manual page is part of the POSIX Programmer’s Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

sem_close — close a named semaphore

  #include <semaphore.h>
  int sem_close(sem_t *sem);

The sem_close/() function shall indicate that the calling process is finished using the named semaphore indicated by /sem. The effects of calling /sem_close/() for an unnamed semaphore (one created by /sem_init/()) are undefined. The /sem_close/() function shall deallocate (that is, make available for reuse by a subsequent /sem_open/() by this process) any system resources allocated by the system for use by this process for this semaphore. The effect of subsequent use of the semaphore indicated by sem by this process is undefined. If any threads in the calling process are currently blocked on the semaphore, the behavior is undefined. If the semaphore has not been removed with a successful call to /sem_unlink/(), then /sem_close/() has no effect on the state of the semaphore. If the sem_unlink/() function has been successfully invoked for /name after the most recent call to /sem_open/() with O_CREAT for this semaphore, then when all processes that have opened the semaphore close it, the semaphore is no longer accessible.

Upon successful completion, a value of zero shall be returned. Otherwise, a value of -1 shall be returned and errno set to indicate the error.

The /sem_close/() function may fail if:

EINVAL

The sem argument is not a valid semaphore descriptor.

The following sections are informative.

None.

None.

None.

None.

/semctl ( )/, /semget ( )/, /semop ( )/, /sem_init ( )/, /sem_open ( )/, /sem_unlink ( )/

The Base Definitions volume of POSIX.1‐2017, <semaphore.h>

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology – Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

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