=========================
 Backuping and restoring
=========================

rsync
=====

Emulate file transfer with ``-n`` or by longer form ``--dry-run``.

Use FS with hardlink with ``cp -l``::

  $ cp -al  /backup/old /backup/new
  $ rsync -a --delete --progress /data/ /backup/new/

Use FS hardlink exclusively with ``rsync``::

  $ rsync -a --delete --progress --link-dest=../previous /data/ /backup/new/

.. note:: ``--link-dest`` accepts a relative path, it is relative to the
          destination directory.

.. note:: Cygwin ``rsync`` implementation can use NTFS hard links with
   ``--link-dest`` option. Check it with::

     cmd> fsutil hardlink list c:\backup\new\file.txt

Avoid carrying permissions and other attributes with::

  --no-p --no-o --no-g --no-A --no-X -O -J

To show current progress::

  -v  --progress

To copy over ssh::

  $ rsync -n -e 'ssh -l $RUSER' -r  /archive/ $RHOST:/archive/
  $ rsync -n -e 'ssh -l $RUSER' -r  /archive/ $RUSER@$RHOST:/archive/

To compare only based on file size use ``--size-only``. In that case ``-t``
option will preserve modification time.