Backing Up and compressing

BACKING UP

$ rsync source-file target:destination-path
where target can be in the form of someone@host. The someone@ part is optional and used if the remote user is different from the local user.

rsync copies the content of the file into another file.

• Automatically checks if the destination file exists
• If there is no change in size and modification time, it avoids the copy
• It copy only the modified part of the file, not the whole file 
• It can copy to a remote destination

Example:

$ rsync -r project-X archive-machine:archives/project-X

dd
Makes a raw copy of an hard disk to another.
Very dangerous if used inappropriately.

COMPRESSING

Efficiency compression max to min and speed compression min to max:

1. xzip
2. bzip2 (deprecated, no longer maintained)
3. gzip
4. tar (most an archiver than a compressor)