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NAME

       sync - commit buffer cache to disk

SYNOPSIS

       #include <unistd.h>

       void sync(void);

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

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

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 3.27 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/.