The Open Group Base Specifications Issue 6
IEEE Std 1003.1, 2004 Edition
Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.

#### NAME

> sem_unlink - remove a named semaphore (REALTIME)

#### SYNOPSIS

> ``[SEM] #include <semaphore.h>
> int sem_unlink(const char *`name`);``
> `
> `

#### DESCRIPTION

> The sem_unlink() function shall remove the semaphore named by the string name. If the semaphore named by name is currently referenced by other processes, then sem_unlink() shall have no effect on the state of the semaphore. If one or more processes have the semaphore open when sem_unlink() is called, destruction of the semaphore is postponed until all references to the semaphore have been destroyed by calls to sem_close(), _exit(), or exec. Calls to sem_open() to recreate or reconnect to the semaphore refer to a new semaphore after sem_unlink() is called. The sem_unlink() call shall not block until all references have been destroyed; it shall return immediately.

#### RETURN VALUE

> Upon successful completion, the sem_unlink() function shall return a value of 0. Otherwise, the semaphore shall not be changed and the function shall return a value of -1 and set errno to indicate the error.

#### ERRORS

> The sem_unlink() function shall fail if:

> [EACCES]
>   Permission is denied to unlink the named semaphore.
> [ENAMETOOLONG]
>   The length of the name argument exceeds {PATH_MAX} or a pathname component is longer than {NAME_MAX}.
> [ENOENT]
>   The named semaphore does not exist.

The following sections are informative.

#### EXAMPLES

> None.

#### APPLICATION USAGE

> The sem_unlink() function is part of the Semaphores option and need not be available on all implementations.

#### RATIONALE

> None.

#### FUTURE DIRECTIONS

> None.

#### SEE ALSO

> semctl(), semget(), semop() , sem_close(), sem_open(), the Base Definitions volume of IEEE Std 1003.1-2001, <semaphore.h>

#### CHANGE HISTORY

> First released in Issue 5. Included for alignment with the POSIX Realtime Extension.

#### Issue 6

> The sem_unlink() function is marked as part of the Semaphores option.

> The [ENOSYS] error condition has been removed as stubs need not be provided if an implementation does not support the Semaphores option.

End of informative text.

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