A spotter’s guide to open-source Linux package formats

By David M Williams
Wednesday, 16 January 2008 17:14

Opinion and Analysis

Want to find open source tools? Linux distros have long had the tradition that software is bundled into easily-installed packages. Yet, finding packages can be less than intuitively obvious and even then they may not appear to be available for your flavour of choice. Here’s how to get the most out of Linux packages.

Actually, the first place to look is your very Linux distribution CD or DVD set. All Linux distros except those of the “damn small” variety ship with much more software on disc than is typically installed. When installing a distro you get a choice as to the kind of system you want often in the form of workstation vs server which installs different combinations of packages.

You can always add to the installed software by using a graphical tool to add (or remove) items, if your distro provides such. In some cases you might need to manually find the raw packages on the original disc but these will generally be located all in one folder with no clear organisation save for the name of the software. That’s fine, unless you only know the type of software you need, not the actual name of something that does it.

Here’s where the Internet always comes in handy. Check out great open source software sites like FreshMeat or Sourceforge. Check them out and search for interesting new apps.

It’s not plain sailing even once you’ve found something: check out MySource Classic for example. This sounds cool; it’s a powerful open source web site and intranet content management system. It is designed to enable technically unskilled users to build and maintain their own online solutions securely, professionally and inexpensively. It’s your classic LAMP app, written in PHP and using Apache and MySQL.

However, MySource Classic is available for download as a .zip file or a .tar.gz file. Both of these are archive formats. Most everyone knows what a zip file is, but .tar.gz – also represented as .tgz – is largely a Linux/UNIX specific format known as a tarball.

Tarballs are convenient formats for distributing source code; it’s pretty universal (harking back to “the old days”, the name tar actually deriving from “tape archive”) and easily transported. However, it’s different from a package format like the apps that come with your Linux distro. Packages contain executable binary files as well as any other configuration items or other files required, and the package manager puts everything in the right place without any effort on your part.

Call up a terminal console and use the tar command to inspect the archive; as with everything Linux there are a few options here.

You can uncompress the tarball using gunzip, namely

gunzip mysource-2.16.2.tar.gz

This leaves a new file called mysource-2.16.2.tar; inspect its contents via

tar –tvf mysource-2.16.2.tar | more

The contents now spill forth. Alternatively, you can examine the original tarball without compressing via a variant of the tar command, namely

tar –tzvf mysource-2.16.2.tar | more

Let’s delve further; we know what the archive contains so let’s crack it open.

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