Updates the i-node table and writes buffered files to the hard disk.
The sync command runs the sync subroutine. If the system must be stopped, run the sync command to ensure file system integrity. The sync command writes all unwritten system buffers to disk including modified i-nodes, delayed block I/O, and read-write mapped files.
Note: The writing, although scheduled, is not necessarily complete upon return from the sync subroutine.
The sync subroutine.