Content-type: text/html Man page of sem_close

sem_close

Section: Realtime Library Functions (3RT)
Updated: 28 Jun 2002
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NAME

sem_close - close a named semaphore  

SYNOPSIS

cc [ flag... ] file... -lrt [ library... ]
#include <semaphore.h>

int sem_close(sem_t *sem);  

DESCRIPTION

The sem_close() function is used to indicate that the calling process is finished using the named semaphore indicated by sem. The effects of calling sem_close() for an unnamed semaphore (one created by sem_init(3RT)) are undefined. The sem_close() function deallocates (that is, make available for reuse by a subsequent sem_open(3RT) by this process) any system resources allocated by the system for use by this process for this semaphore. The effect of subsequent use of the semaphore indicated by sem by this process is undefined. If the semaphore has not been removed with a successful call to sem_unlink(3RT), then sem_close() has no effect on the state of the semaphore. If the sem_unlink(3RT) function has been successfully invoked for name after the most recent call to sem_open(3RT) with O_CREAT for this semaphore, then when all processes that have opened the semaphore close it, the semaphore is no longer be accessible.  

RETURN VALUES

If successful, sem_close() returns 0, otherwise it returns -1 and sets errno to indicate the error.  

ERRORS

The sem_close() function will fail if:

EINVAL The sem argument is not a valid semaphore descriptor.

ENOSYS The sem_close() function is not supported by the system.

 

USAGE

The sem_close() function should not be called for an unnamed semaphore initialized by sem_init(3RT).  

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPEATTRIBUTE VALUE
Interface StabilityStandard
MT-Level MT-Safe

 

SEE ALSO

sem_init(3RT), sem_open(3RT), sem_unlink(3RT), attributes(5), standards(5)  

NOTES

Solaris 2.6 was the first release to support the Asynchronous Input and Output option. Prior to this release, this function always returned -1 and set errno to ENOSYS.


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUES
ERRORS
USAGE
ATTRIBUTES
SEE ALSO
NOTES

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Time: 02:39:04 GMT, October 02, 2010