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(3),
_exit(3), or
exec.
Calls to sem_open(3) 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(3), semget(3), semop(3) , sem_close(3), sem_open(3), the Base Definitions volume of IEEE Std 1003.1-2001 (“POSIX.1”), <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.
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