In this article I am going to de-mystify Linux file compression and archiving for you. By the end of the article you’ll be compressing and decompressing files in your sleep. And, as a bonus, you’ll know how to do this both via command line and GUI.

Compression versus archiving

The difference between compression and archiving is simple: Compression makes a file (or directory) smaller and Archiving takes many seperate files (such as a directory containing sub-directories and/or files) and turns it into a single file. You can have a compressed archive (such as .tar.gz or .tgz) and you can even have an archive of compressed files (such as a directory that contains a bunch of compressed files). But how do you know what are compressed files verses archived files? Here’s a list of file extensions and what they are.

.tar – This is an uncompressed Tar archive file. This type of archive is unpacked with the command tar xvf file.tar.

.tgz – This is a compressed Tar archive file. This type of archive is decompressed and unpacked with the command tar xvzf file.tgz.

.gz – This is a file compressed with the gzip program. This type of file is decompressed with the command gunzip file.gz.

.zip – This is a compressed file. This type of file is decompressed with the command unzip file.zip

.bz2 – This is a compressed file. This type of file is decompressed with the command bunzip2 file.bz2.

Which compression to use?

Of the three compression utilities (bzip2, zip, and gzip) the tool that will result in the most compression (the smallest file) is bzip2. The only disadvantage to bzip2 is that the algorithm uses more processor to complete than does the other utilities.

If you are sharing your compressed files with Windows users your best bet is to use zip for compression. Although there are tools (such as Stuffit Deluxe for Windows) that can handle bz2 files, the default supported is .zip.

Using the GUI

If you are a fan of the GUI (and who isn’t these days?) you will be glad to know that most all Linux file managers can handle compressed and archived files. In both Nautilus (GNOME) and Dolphin (KDE) you can simply right click a compressed, archived, or compressed archive file and select Extract. Both file managers also offer compression and archiving options when you right click a file or directory.

Final thoughts

Working with compression and archiving is very simple with the Linux operating system. You have plenty of options in both the command line and the GUI worlds.

Users with T1 connections, that is 1.44 Mbps would have to wait 9.28 seconds. The figures are of course only valid if they do not use part of their download speed for other transfers at the same time. The first thing that I decided to do was to enable gzip compression in the Wordpress options in the reading tab. Before I enabled it I did a quick check that my server was actually able to gzip by using the simple phpinfo() command.

I tested the result and the page size went down almost 35%! It went down 58K to 108K total. The time users with ISDN had to wait before the full page is loaded was reduced by almost 4 seconds from 18.55 seconds to 14.80 seconds. The loading time for T1 users was reduced by 0.51 seconds to 8.77 seconds in total.

I still did not apply the optimization that Paul suggested and that is what I intended to do next. His suggestion was to gzip compress the css file as well to reduce loading time even further. I found a reference to a nice Wordpress plugin in the comments of his post. The plugin is called css-compress. It just has to be activated in the plugin tab in Wordpress. The advantage of using css-compress over Paul’s method is that css compress compresses all css files even those of third parties such as those from advertisers or other plugins.

Another check reported that the total size of my blogs frontpage was again reduced by almost 10k from 108K to 98K. Loading time was again reduced by 1.17 seconds for ISDN users and 0.65 seconds for users with a T1 connection.

I was not able to witness any negative effects on my blogs design, the functions or server load. Sure it uses a little bit processing power but this should only be a problem for weak shared hosts.

You can check the loading speed of websites using the nice script available at website optimization.