Linux manual pages Section 2  

Name

sync — commit buffer cache to disk

Synopsis

#include <unistd.h>
void sync( void);  
 
[Note] Note
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
sync():
_BSD_SOURCE || _XOPEN_SOURCE >= 500

DESCRIPTION

sync() first commits inodes to buffers, and then buffers to disk.

ERRORS

This function is always successful.

CONFORMING TO

SVr4, 4.3BSD, POSIX.1-2001.

NOTES

Since glibc 2.2.2 the Linux prototype is as listed above, following the various standards. In libc4, libc5, and glibc up to 2.2.1 it was "int sync(void)", and sync() always returned 0.

BUGS

According to the standard specification (e.g., POSIX.1-2001), sync() schedules the writes, but may return before the actual writing is done. However, since version 1.3.20 Linux does actually wait. (This still does not guarantee data integrity: modern disks have large caches.)

SEE ALSO

bdflush(2), fdatasync(2), fsync(2), sync(8), update(8)

COLOPHON

This page is part of release 3.24 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.


Copyright (c) 1992 Drew Eckhardt (drewcs.colorado.edu), March 28, 1992

Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
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Modified by Michael Haardt <michaelmoria.de>
Modified Sat Jul 24 12:02:47 1993 by Rik Faith <faithcs.unc.edu>
Modified 15 Apr 1995 by Michael Chastain <mecshell.portal.com>:
  Added reference to `bdflush(2)'.
Modified 960414 by Andries Brouwer <aebcwi.nl>:
  Added the fact that since 1.3.20 sync actually waits.
Modified Tue Oct 22 22:27:07 1996 by Eric S. Raymond <esrthyrsus.com>
Modified 2001-10-10 by aeb, following Michael Kerrisk.