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

NAME

       sync, syncfs - commit buffer cache to disk

SYNOPSIS

       #include <unistd.h>

       void sync(void);

       int syncfs(int fd);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       sync():
	   _BSD_SOURCE || _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED

       syncfs():
	   _GNU_SOURCE

DESCRIPTION

       sync() causes all buffered modifications to file metadata and data to be written to the underlying file systems.

       syncfs() is like sync(), but synchronizes just the file system containing file referred to by the open file descriptor fd.

RETURN VALUE

       syncfs() returns 0 on success; on error, it returns -1 and sets errno to indicate the error.

ERRORS

       sync() is always successful.

       syncfs() can fail for at least the following reason:

       EBADF  fd is not a valid file descriptor.

VERSIONS

       syncfs() first appeared in Linux 2.6.39; library support was added to glibc in version 2.14.

CONFORMING TO

       sync(): SVr4, 4.3BSD, POSIX.1-2001.

       syncfs() is Linux-specific.

NOTES

       Since  glibc  2.2.2  the  Linux prototype for sync() 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 3.53 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/.

Linux								    2012-05-04								   SYNC(2)