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 removal and
removed when there are no more processes referencing it.
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.
STANDARDS CONFORMANCE
sem_unlink(): POSIX
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