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CLOSE(2)		   Linux Programmer's Manual		      CLOSE(2)

NAME
       close - close a file descriptor

SYNOPSIS
       #include	<unistd.h>

       int close(int fd);

DESCRIPTION
       close()	closes	a  file	descriptor, so that it no longer refers	to any
       file and	may be reused.	Any record locks (see fcntl(2))	 held  on  the
       file it was associated with, and	owned by the process, are removed (re-
       gardless	of the file descriptor that was	used to	obtain the lock).

       If fd is	the last file descriptor referring to the underlying open file
       description  (see open(2)), the resources associated with the open file
       description are freed; if the descriptor	was the	last  reference	 to  a
       file which has been removed using unlink(2), the	file is	deleted.

RETURN VALUE
       close()	returns	 zero on success.  On error, -1	is returned, and errno
       is set appropriately.

ERRORS
       EBADF  fd isn't a valid open file descriptor.

       EINTR  The close() call was interrupted by a signal; see	signal(7).

       EIO    An I/O error occurred.

CONFORMING TO
       SVr4, 4.3BSD, POSIX.1-2001.

NOTES
       Not checking the	return value of	close()	is a common  but  nevertheless
       serious	programming error.  It is quite	possible that errors on	a pre-
       vious write(2) operation	are first reported at the final	close().   Not
       checking	the return value when closing the file may lead	to silent loss
       of data.	 This can especially be	observed with NFS and with disk	quota.
       Note  that  the	return	value should only be used for diagnostics.  In
       particular close() should not be	retried	after an EINTR since this  may
       cause a reused descriptor from another thread to	be closed.

       A  successful  close does not guarantee that the	data has been success-
       fully saved to disk, as the kernel defers writes.  It is	not common for
       a  filesystem  to  flush	the buffers when the stream is closed.	If you
       need to be sure that the	data is	physically stored, use fsync(2).   (It
       will depend on the disk hardware	at this	point.)

       It  is  probably	 unwise	to close file descriptors while	they may be in
       use by system calls in other threads in the same	process.  Since	a file
       descriptor  may	be reused, there are some obscure race conditions that
       may cause unintended side effects.

SEE ALSO
       fcntl(2), fsync(2), open(2), shutdown(2), unlink(2), fclose(3)

COLOPHON
       This page is part of release 3.74 of the	Linux  man-pages  project.   A
       description  of	the project, information about reporting bugs, and the
       latest	 version    of	  this	  page,	   can	   be	  found	    at
       http://www.kernel.org/doc/man-pages/.

Linux				  2013-12-30			      CLOSE(2)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

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