flushes all data buffers of a file to disk (before the system
call returns).
It resembles
-.BR fsync ()
+.BR fsync (2)
but is not required to update the metadata such as access time.
Applications that access databases or log files often write a tiny
data fragment (e.g., one line in a log file) and then call
-.BR fsync ()
+.BR fsync (2)
immediately in order to ensure that the written data is physically
stored on the harddisk.
Unfortunately,
-.BR fsync ()
+.BR fsync (2)
will always initiate two write operations: one for the newly written
data and another one in order to update the modification time stored
in the inode.
Currently (Linux 2.2)
.BR fdatasync ()
is equivalent to
-.BR fsync ().
+.BR fsync (2).
.SH AVAILABILITY
On POSIX systems on which
.BR fdatasync ()