Friday, 4 June 2010

Downloading Source Code - What and Why?

You know what one of the biggest pains in the arse is for a new open source user? Open source code.

Yeah, who'da thunk it?

Y'see with windows flavour operating system you download a program. You usually get an install file which you double click, progress through some questions about where you want to install the software, delete the name of the software writer in the install path so you can actually find the fucker in "Program Files" in the future, and click on install.

You then just run the software from a shortcut on the desktop or the Start Menu. Usually either the desktop or the start menu gets bloated with entries to the point where you have to buy a new computer.

Alternatively, you can download a zip file, which you just uncompress to a folder and then make your own shortcuts, and just run the program from that folder.

When you 'run' a program, what I mean is that you execute a file. This is usually a file with the extension .exe, or sometimes .com. Occasionally you run a batch file (extension .bat) which then handles the execution of the .exe file in due course.

With an advanced distribution of Linux, such as Ubuntu, you install new programs using a package management facility. What this means is that Canonical, the company behind Ubuntu, maintain a collection of software that is 'approved' to work with Ubuntu. The installation of the software is completely automated, once you have chosen it in the software store.

Ubuntu, in effect, handles the downloading, and installing of the software. You are left with a menu entry to run the software.

This is, actually, really easy. Like many things that are really easy it is also inflexible. Go on, try and reorganise your menu entries. I dare you.

So what if you want to install software that is not on Ubuntu's approved list? Well then we go from 'really easy' to mind disturbingly fucking hard.

Occasionally, just occasionally, software is provided for download in the same sense as windows install files. You get an archive containing the program files, and any support files. You install the software by double clicking the file (or by typing some ludicrously long command at the command line). The archive itself has a set of instructions built in that tells it where to install the files to, and where (or if) to make the menu entry. So far so good.

However, different distributions of Linux organise their file structures in different ways. So software may be installed in the Linux equivalent of: C:\Program Files\[location] or C:\Application Files\[location] or C:\Some Other Weird Place\[location], depending on your particular distribution. This means that one archive will not work on all distributions of Linux. Ubuntu and other Debian based distributions install archives are called .deb files. Fedora, and other Redhat based distributions use .rpm files.

You cannot use .rpm files on a system expecting .deb files and vice versa (well, OK, if you use a package converter you might be able to. Best of luck with that, let me know how the reinstall goes).

OK, so we have the Distribution approved files in their collections (known as repositories), we have a small fraction of software developers who go to the trouble of making a .deb AND a .rpm AND a .whatever file for their software. What about the other software that you may find in random places in the internet? What about the software that you download in a .tar.gz or a .tar.bz2 file? What the fuck do you do with these? And why would you want to have anything to do with them anyway?

You will eventually encounter and download these files because, while the repository system is useful, it does not have all the software that you may want, or if it does it may not be the version you want. See for instance my vocal complaint about the version of ALSA that came with Ubuntu Karmic. It needed to be upgraded to a newer version, but that version was not supported by Karmic (it is by Intrepid).

Also, some software may be so new it is simply not included in the formal repository system. Lastly, the software may be deliberately excluded from the repositories for intellectual property reasons (if all the source is not free for instance).

See next time for more exciting revelations about source code! Gasp in awe as I try in vain to run a program by making HandBrake-0.9.4.tar.bz2 an executable file and typing its name! Groan in agony as you realise that after downloading the 32k file you have also to download 100Mb of other software just to get it to work - its .net all over a-fucking-gain!

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