HP-UX Reference (11i v1 00/12) - 2 System Calls (vol 5)

ManualsBrandsHP ManualsSoftwareHP-UX Reference Manuals

291

292

293

294

295

296

297

298

299

300

__________________________________________________________________________________________________________________________________________________________________________________________________

STANDARD Printed by: Nora Chuang [nchuang] STANDARD

/build/1111/BRICK/man2/!!!intro.2

________________________________________________________________

___ ___

sem_close(2) sem_close(2)

NAME

sem_close - close a named POSIX semaphore

SYNOPSIS

#include <sys/semaphore.h>

int sem_close(sem_t *sem);

DESCRIPTION

sem_close() is used to close a named semaphore. A successful call to sem_close() will do the fol-

lowing: Remove the process’s descriptor for the semaphore referenced by the speciﬁed sem_t structure

sem. Remove the semaphore referenced by the speciﬁed sem_t structure sem, if the semaphore is marked

for removal by a call to sem_unlink() and there are no other descriptors referencing this semaphore.

When the process’s descriptor for the semaphore referenced by sem is removed, subsequent use of this

semaphore by this process will fail. Descriptors for named semaphores are also removed by processes on

exit. Calling sem_close() does not affect other processes referencing the same 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_close() will close a named semaphore referred to by sem by removing the

process’s descriptor to the semaphore and removing the semaphore if it is marked for removal by a previ-

ous

sem_unlink() and there are no descriptors referencing it.

sem_close(sem);

RETURN VALUE

If the semaphore was closed and the descriptors referencing it were removed, sem_close() returns 0 to

the caller.

If the semaphore could not be closed, the call returns -1 and sets errno to indicate the error.

ERRORS

sem_close() fails and does not perform the requested operation if the following condition is encoun-

tered:

[EINVAL] The argument sem is not a valid named semaphore.