tar

The system administrator routinely performs backups of all user files. In the event of a disk failure, your files could be restored from these backups. However, any changes made to the files or any new files added since the last backup cannot be restored. This can be a catastrophic event. If you have files which are critical to your work, you may want to consider performing your own backups. Also, if you have files which you are not using, and you are ready only keeping "just in case", you should use the same techniques to achieve your data on tape and remove it from the disk to free up space for your current work (this kind of thing is greatly appreciated by the sysadmin and other users, too.)

tar is the tape archiver. It takes the contents of a directory and all of its subdirectories and creates an archive file, writing the file to an archiving device (usually a tape drive). To use tar, type the following:

% tar -cvf archiveName.tar directoryName

The c option tells tar to create a new archive. The v option selects verbose mode, so you can see the files that tar is archiving. directoryName specifies which directory to archive. tar will archive all of the files underneath this directory (including subdirectories) and write the archive archiveName, which can specify a file or a special file representing the tape device.

% gzip archiveName.tar (It produces archiveName.tar.gz)

In order to uncompress a file with .tar.gz, you can issue the following commands:

% gunzip fileName.tar.gz (It produces fileName.tar)
% tar -xvf fileName.tar (It produces the original directory.)