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sem_unlink.2 (2010 09)

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sem_unlink(2) sem_unlink(2)
NAME
sem_unlink - unlink a named POSIX semaphore
SYNOPSIS
#include <sys/semaphore.h>
int sem_unlink(const char *name);
DESCRIPTION
sem_unlink() is used to unlink named semaphores. A successful call to
sem_unlink() marks the
semaphore, specified by name , for removal. Calling
sem_unlink() does not affect processes, including
the calling process, which currently have a descriptor, obtained from a call to
sem_open(). Named
semaphores are uniquely identified by character strings. All character string names will be pre-processed
to ensure variations of a pathname resolve to the same semaphore name. If the semaphore is successfully
marked for removal by a call to
sem_unlink()
, the semaphore will be removed when all processes
remove their descriptors to the specified semaphore by calling
sem_close(). Subsequent calls to
sem_open() using the string name will refer to a new semaphore.
To use this function, link in the realtime library by specifying
-lrt on the compiler or linker command
line.
EXAMPLES
The following call to
sem_unlink() will remove the named semaphore named by the string name .If
the semaphore is currently referenced by one or more processes, the semaphore will be marked for remo-
val and removed when there are no more processes referencing it.
sem_unlink(name);
RETURN VALUE
If the semaphore was unlinked successfully,
sem_unlink() returns 0.
If the semaphore could not be unlinked, the call returns -1 and sets
errno to indicate the error.
ERRORS
sem_unlink() fails and does not perform the requested operation if any of the following conditions are
encountered:
[EACCES] The named semaphore exists and the process does not have the permissions to
unlink the semaphore.
[ENAMETOOLONG]
The name string is longer than
{PATH_MAX}.
[ENOENT] The flag
O_CREAT is not set in oflag (see sem_open (2)) and the named semaphore
does not exist.
SEE ALSO
sem_close(2), sem_open(2), privileges(5), <semaphore.h>.
STANDARDS CONFORMANCE
sem_unlink(): POSIX
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1

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