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* The Unix tar function combines files and puts them into one file.  It does
* not compress files so it makes no sense to tar one file.  Typically we tar
* all the files in a particular directory.  We use the gzip utility to 
* compress files. If you see a file like filename.tar.gz it contains a number 
* of files that have been tarred together and then compressed.
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To create a tar file: cd to parent of directory to be tarred.

Type: tar -cvpf your_filename.tar directory_name
This results in: your_filename.tar

       a) use r instead of c to replace (append)
       b) use u instead of c to replace (update) 
       c) NB: Use a relative file reference for directory! This allows easy 
          move of file tree

To create a compressed version of this tar file:

Type: gzip your_filename.tar.  Result will be your_filename.tar.gz
 
To uncompress your your_filename.tar.gz type: gzip -d your_filename.tar.gz. 
This results in: your_filename.tar

To extract (untar) the individual files type: tar -xvpf your_filename.tar

       a) tar -tvf your_filename.tar to just list the files.

Note 1: The purpose of compressing files is to save space so once a directory 
has been tarred and compressed we would typically delete that directory and 
all the files in it.  The command would be /usr/bin/rm -r directory_name.
Be careful when deleting files.

Note 2: compress and compress -d is a substitute for gzip -9 and gzip -d.