The common UNIX command tar is a utility originally devised to create tape archives for the purpose of backing files up onto computer tapes.

While tar is still used to create tape backups of file systems, it has become far more common to use tar to group files and/or directories together into a single entity, typically called a "tar-ball" or "tarball." (So common is the use of tar that it has been verbed in computer science terminology: We speak of "tarring" files, or files that have been "tarred up.") Tar syntax is somewhat arcane, as tar came into existence before modern standards for command-line options.

To unpack the starting skeleton code for project:

• Login to Morbius (or any of the other Systems Lab machines and change to your working directory.
• Execute the the following command:
      tar xvzf ~brylow/os/Projects/xinu-hw3.tgz

This untars the files for xinu-hw3 into your working directory, in a subdirectory called xinu-hw3.

In this particular example, the parameters to tar stand for:

• x = extract the files from the tarball. As opposed to create or tell what is in a tarball,
• v = verbose, which instructs tar to list all of the files it is reading or writing,
• z = gzip or gunzip (depending on context) the tarball. Other compression options include j for bzip2, and
• f = file, indicating that the next argument to follow witll be the tarball filename.

For more information on tar, please see the UNIX man pages.