useful stuff about tar

tar will generally overwrite already existing files when untarring. There is the '-k' switch which tells it to keep old files. It will not erase files that are not in the tarball being extracted though. From the '--help':

-k, --keep-old-files don't replace existing files when extracting
--keep-newer-files don't replace existing files that are newer
than their archive copies
--overwrite overwrite existing files when extracting
--no-overwrite-dir preserve metadata of existing directories



When you extract a tarball as root, it will extract the file with the same UID as it was created with. I found this out in an amusing way when attempting to extract a tarball I'd downloaded, and it would fail with the message 'quota exceeded'. This was because the UID of the files in the tarball were the same as one of the users on the box. '--no-same-owner' will extract them as your current ID, which is the default for non-root.

Tar across the network, using ssh:

tar -czf - ~/mp3s | ssh 192.168.1.163 tar -xvzf -