Lesson 18: Archiving

The collection of many files into a single archive file (often referred to as a tarball) can be achieved using the tar command. Archive files are common in software distribution and backups.

Creating an Archive

An archive can be created using the -cf switch combination. The command tar needs to know what to call the archive file, and what files to archive. It is possible to use a compression library to reduce the size of the archive. Gzip is an example compression library which can be invoked by passing the -z switch. See the manual page for other types of compression.

Let's touch some additional files, then archive and compress them:

[learner ~]$ cd learning_linux/planets
[learner planets]$ touch earth.{html,xml}
[learner planets]$ tar -czf earth.tar.gz earth.*
[learner planets]$ ls earth*
earth.html  earth.tar.gz  earth.txt  earth.xml

The standard file format for tarballs is .tar (un-compressed) and .tar.gz (compressed using Gzip).

Listing Archive Contents

The contents of an existing archive (regardless of compression), can be listed using the -tf switch combination.

[learner planets]$ tar -tf earth.tar.gz
earth.html
earth.txt
earth.txt.bak
earth.xml

Extracting Files from an Archive

The contents of an existing archive can be extracted using the -xf switch combination. If the archive has been compressed using Gzip, the -z switch needs also to be present. By default, the extraction destination is the current working directory, but a custom directory can be provided with the -C switch.

[learner planets]$ tar -xzf earth.tar.gz -C ..
[learner planets]$ ls ..
earth.html  earth.txt  earth.txt.bak  earth.xml  planets