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.

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.