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 filesystems.

       syncfs() is like sync(), but synchronizes just the filesystem 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 3.54 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/.