mirror of https://github.com/mkerrisk/man-pages
114 lines
3.6 KiB
Groff
114 lines
3.6 KiB
Groff
.\" Hey Emacs! This file is -*- nroff -*- source.
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.\"
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.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
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.\" 1993 Michael Haardt, Ian Jackson.
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" Modified Wed Jul 21 22:40:25 1993 by Rik Faith <faith@cs.unc.edu>
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.\" Modified Sat Feb 18 15:27:48 1995 by Michael Haardt
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.\" Modified Sun Apr 14 11:40:50 1996 by Andries Brouwer <aeb@cwi.nl>:
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.\" corrected description of effect on locks (thanks to
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.\" Tigran Aivazian <tigran@sco.com>).
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.\" Modified Fri Jan 31 16:21:46 1997 by Eric S. Raymond <esr@thyrsus.com>
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.\" Modified 2000-07-22 by Nicolás Lichtmaier <nick@debian.org>
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.\" added note about close(2) not guaranteeing that data is safe on close.
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.\"
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.TH CLOSE 2 2001-12-13 "" "Linux Programmer's Manual"
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.SH NAME
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close \- close a file descriptor
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.SH SYNOPSIS
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.nf
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.B #include <unistd.h>
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.sp
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.BI "int close(int " fd );
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.fi
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.SH DESCRIPTION
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.BR close ()
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closes a file descriptor, so that it no longer refers to any file and
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may be reused.
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Any record locks (see
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.BR fcntl (2))
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held on the file it was associated with,
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and owned by the process, are removed (regardless of the file
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descriptor that was used to obtain the lock).
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.PP
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If
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.I fd
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is the last copy of a particular file descriptor the resources
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associated with it are freed;
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if the descriptor was the last reference to a file which has been
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removed using
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.BR unlink (2)
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the file is deleted.
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.SH "RETURN VALUE"
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.BR close ()
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returns zero on success.
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On error, \-1 is returned, and
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.I errno
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is set appropriately.
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.SH ERRORS
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.TP
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.B EBADF
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.I fd
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isn't a valid open file descriptor.
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.TP
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.B EINTR
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The
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.BR close ()
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call was interrupted by a signal.
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.TP
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.B EIO
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An I/O error occurred.
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.SH "CONFORMING TO"
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SVr4, 4.3BSD, POSIX.1-2001.
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.\" SVr4 documents an additional ENOLINK error condition.
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.SH NOTES
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Not checking the return value of
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.BR close ()
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is a common but nevertheless
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serious programming error.
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It is quite possible that errors on a
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previous
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.BR write (2)
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operation are first reported at the final
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.BR close ().
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Not checking the return value when closing the file may lead to
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silent loss of data.
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This can especially be observed with NFS
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and with disk quota.
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.PP
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A successful close does not guarantee that the data has been successfully
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saved to disk, as the kernel defers writes.
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It is not common for a filesystem
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to flush the buffers when the stream is closed.
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If you need to be sure that
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the data is physically stored use
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.BR fsync (2).
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(It will depend on the disk hardware at this point.)
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.SH "SEE ALSO"
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.BR fcntl (2),
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.BR fsync (2),
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.BR open (2),
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.BR shutdown (2),
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.BR unlink (2),
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.BR fclose (3)
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