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/.