close(2)                                                    close(2)


       NAME
             close - close a file descriptor

       SYNOPSIS
             #include <unistd.h>
             int close(int fildes);

       DESCRIPTION
             close closes a file.  fildes is a file descriptor obtained
             from a creat, open, dup, fcntl, pipe, or iocntl system call.
             close closes the file descriptor indicated by fildes.  All
             outstanding record locks owned by the process (on the file
             indicated by fildes) are removed.

             Closing a file descriptor removes one reference to the
             associated file.  When there are no more outstanding
             references to the file, if the link count of the file is zero,
             the space occupied by the file shall be freed and the file
             shall no longer be accessible.

             If a STREAMS-based [see intro(2)] fildes is closed, and the
             calling process had previously registered to receive a SIGPOLL
             signal [see signal(5)] for events associated with that stream
             [see I_SETSIG in streamio(7)], the calling process will be
             unregistered for events associated with the stream.  The last
             close for a stream causes the stream associated with fildes to
             be dismantled.  If O_NDELAY and O_NONBLOCK are clear and there
             have been no signals posted for the stream, and if there are
             data on the module's write queue, close waits up to 15 seconds
             (for each module and driver) for any output to drain before
             dismantling the stream.  The time delay can be changed via an
             I_SETCLTIME ioctl request [see streamio(7)].  If O_NDELAY or
             O_NONBLOCK is set, or if there are any pending signals, close
             does not wait for output to drain, and dismantles the stream
             immediately.

             If fildes is associated with one end of a pipe, the last close
             causes a hangup to occur on the other end of the pipe.  In
             addition, if the other end of the pipe has been named [see
             fattach(3C)], the last close forces the named end to be
             detached [see fdetach(3C)].  If the named end has no open
             processes associated with it and becomes detached, the stream
             associated with that end is also dismantled.





                           Copyright 1994 Novell, Inc.               Page 1

      close(2)                                                    close(2)


         Return Values
            On success, close returns 0.  On failure, close returns -1 and
            sets errno to identify the error.

         Errors
            In the following conditions, close fails and sets errno to:

            EBADF          fildes is not a valid open file descriptor.

            EINTR          A signal was caught during the close system
                           call.

            ENOLINK        fildes is on a remote machine and the link to
                           that machine is no longer active.

      REFERENCES
            creat(2), dup(2), exec(2), fattach(3C), fcntl(2), fdetach(3C),
            intro(2), open(2), pipe(2), signal(2), signal(5), streamio(7)

      NOTICES
         Considerations for Threads Programming
            Open file descriptors are global to the process and accessible
            to any sibling thread.  If used concurrently, actions by one
            thread can interfere with those of a sibling.

            A close executed by one thread will render the file descriptor
            unusable by all siblings.  The close system call will block a
            thread that attempts to close a file descriptor that is in use
            (mid-system call) by a sibling.



















                          Copyright 1994 Novell, Inc.               Page 2