semaphore.h(3head) [centos man page]

semaphore.h(3HEAD)                                                    Headers                                                   semaphore.h(3HEAD)

NAME

       semaphore.h, semaphore - semaphores

SYNOPSIS

       #include <semaphore.h>

DESCRIPTION

       The  <semaphore.h>  header  defines  the sem_t type, used in performing semaphore operations. The semaphore can be implemented using a file
       descriptor, in which case applications are able to open up at least a total of {OPEN_MAX} files and semaphores. The  symbol  SEM_FAILED  is
       defined (see sem_open(3RT)).

       Inclusion  of  the <semaphore.h> header can make visible symbols defined in the headers <fcntl.h> and <sys/types.h>. See fcntl.h(3HEAD) and
       types.h(3HEAD).

ATTRIBUTES

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

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE         |      ATTRIBUTE VALUE        |
       +-----------------------------+-----------------------------+
       |Interface Stability          |Standard                     |
       +-----------------------------+-----------------------------+

SEE ALSO

       fcntl.h(3HEAD), types.h(3HEAD),  sem_destroy(3RT),  sem_getvalue(3RT),  sem_init(3RT),  sem_open(3RT),  sem_post(3RT),  sem_timedwait(3RT),
       sem_unlink(3RT), sem_wait(3RT), attributes(5), standards(5)

SunOS 5.10                                                          10 Sep 2004                                                 semaphore.h(3HEAD)

sem_close(3RT)						    Realtime Library Functions						    sem_close(3RT)

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  sema-
       phore, 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 TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |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.

SunOS 5.10							    28 Jun 2002 						    sem_close(3RT)