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# The Debian GNU/Linux FAQ
Chapter 3 - Choosing a Debian distribution

There are many different Debian distributions. Choosing the proper Debian distribution is an important decission. This section covers some information useful for users that want to make the choice best suited for their system and also answers possible questions that might be arising during the process. It does not deal with "why you should choose Debian" but rather "which distribution of Debian".

For more information on the available distributions read How many Debian distributions are there?, Section 6.1.

## 3.1 Which Debian distribution (stable/testing/unstable) is better for me?

The answer is a bit complicated. It really depends on what you intend to do. One solution would be to ask a friend who runs Debian. But that does not mean that you cannot make an independent decision. In fact, you should be able to decide once you complete reading this chapter.

- If security or stability are at all important for you: install stable. period. This is the most preferred way.

- If you are a new user installing to a desktop machine, start with stable. Some of the software is quite old, but it's the least buggy environment to work in. You can easily switch to the more modern unstable once you are a little more confident.

- If you are a desktop user with some experience in Linux and does not mind facing the odd bug now and then, use unstable. It has all the latest and greatest software, and bugs are usually fixed swiftly.

- If you are running a server, especially one that has strong stability requirements or is exposed to the Internet, install stable. This is by far the strongest and safest choice.

The following questions (hopefully) provide more detail on these choices. After reading this whole FAQ, if you still could not make a decision, stick with the stable distribution.

### 3.1.1 You asked me to install stable, but in stable so and so hardware is not detected/working. What should I do?

Try to search the web using a search engine and see if someone else is able to get it working in stable. Most of the hardware should work fine with stable. But if you have some state-of-the-art, cutting edge hardware, it might not work with stable. If this is the case, you might want to install/upgrade to unstable.

For laptops, `http://www.linux-on-laptops.com/` is a very good website to see if someone else is able to get it to work under Linux. The website is not specific to Debian, but is nevertheless a tremendous resource. I am not aware of any such website for desktops.

Another option would be to ask in the debian-user mailing list by sending an email to debian-user@lists.debian.org . Messages can be posted to the list even without subscribing. The archives can be read through `http://lists.debian.org/debian-user/` Information regarding subscribing to the list can be found at the location of archives. You are strongly encourage to post your questions on the mailing-list than on `irc`. The mailing-list messages are archived, so solution to your problem can help others with the same issue.

### 3.1.2 Will there be different different versions of packages in different distributions?

Yes. Unstable has the most recent (latest) versions. But the packages in unstable are not well tested and might have bugs.

On the other hand, stable contains old versions of packages. But this package is well tested and is less likely to have any bugs.

The packages in testing fall between these two extremes.

### 3.1.3 The stable distributions really contains outdated packages. Just look at Kde, Gnome, Xorg or even the kernel. They are very old. Why is it so?

Well, you might be correct. The age of the packages at stable depends on when the last release was made. Since there is typically over 1 year between releases you might find that stable contains old versions of packages. However, they have been tested in and out. One can confidently say that the packages do not have any known severe bugs, security holes etc., in them. The packages in stable integrate seamlessly with other stable packages. These characteristics are very important for production servers which have to work 24 hours a day, 7 days a week.

On the other hand, packages in testing or unstable can have hidden bugs, security holes etc., Moreover, some packages in testing and unstable might not be working as intended. Usually people working on a single desktop prefer having the latest and most modern set of packages. Unstable is the solution for this group of people.

As you can see, stability and novelty are two opposing ends of the spectrum. If stability is required: install stable distribution. If you want to work with the latest packages, then install unstable.

### 3.1.4 If I were to decide to change to another distribution, Can I do that?

Yes, but it is a one way process. You can go from stable --> testing --> unstable. But the reverse direction is not "possible". So better be sure if you are planning to install/upgrade to unstable.

Actually, if you are an expert and if you are willing to spend some time and if you are real careful and if you know what you are doing, then it might be possible to go from unstable to testing and then to stable. The installer scripts are not designed to do that. So in the process, your configuration files might be lost and....

### 3.1.5 Could you tell me whether to install testing or unstable?

This is a rather subjective issue. There is no perfect answer but only a "wise guess" could be made while deciding between unstable and testing. My personal order of preference is Stable, Unstable and Testing. The issue is like this:

- Stable is rock solid. It does not break.

- Testing breaks less often than Unstable. But when it breaks, it takes a long time for things to get rectified. Sometimes this could be days and it could be months at times.

- Unstable changes a lot, and it can break at any point. However, fixes get rectified in many occasions in a couple of days and it always has the latest releases of software packaged for Debian.

But there are times when tracking testing would be beneficial as opposed to unstable. The author such situation due to the gcc transition from gcc3 to gcc4. He was trying to install the `labplot` package on a machine tracking unstable and it could not be installed in unstable as some of its dependencies have undergone gcc4 transition and some have not. But the package in testing was installable on a testing machine as the gcc4 transitioned packages had not "trickled down" to testing.

### 3.1.6 You are talking about testing being broken. What do you mean by that?

Sometimes, a package might not be installable through package management tools. Sometimes, a package might not be available at all, maybe it was (temporarily) removed due to bugs or unmet dependencies. Sometimes, a package installs but does not behave in the proper way.

When these things happen, the distribution is said to be broken (at least for this package).

### 3.1.7 Why is it that testing could be broken for months? Wont the fixes introduced in unstable flow directly down into testing?

The bug fixes and improvements introduced in the unstable distribution trickle down to testing after a certain number of days. Let's say this threshold is 10 days. The packages in unstable go into testing only when there are no RC-bugs reported against them. If there is a RC-bug filed against a package in unstable, it will not go into testing after the 10 days.

The idea is that, if the package has any problems, it would be discovered by people using unstable and will be fixed before it enters testing. This keeps the testing in an usable state for most period of the time. Overall a brilliant concept, if you ask me. But things are alwasy not so simple. Consider the following situation:

- Imagine you are interested in package XYZ.

- Let's assume that on June 10, the version in testing is XYZ-3.6 and in unstable it is XYZ-3.7

- After 10 days, XYZ-3.7 from unstable migrates into testing.

- So on June 20, both testing and unstable have XYZ-3.7 in their repositories.

- Let's say, The user of testing distribution sees that a new XYZ package is available and updates his XYZ-3.6 to XYZ-3.7

- Now on June 25, someone using testing or unstable discovers an RC bug in XYZ-3.7 and files it in the BTS.

- The maintainer of XYZ fixes this bug and uploads it to unstable say on June 30. Here it is assumed that it takes 5 days for the maintainer to fix the bug and upload the new version. The number 5 should not be taken literally. It could be less or more, depending upon the severity of the RC-bug at hand.

- This new version in unstable, XYZ-3.8 is scheduled to enter testing on July 10th.

- But on July 5th some other person, discovers another RC-bug in XYZ-3.8

- Let's say the maintainer of XYZ fixes this new RC-bug and uploads new version of XYZ after 5 days.

- So on July 10, testing has XYZ-3.7 while unstable has XYZ-3.9

- This new version XYZ-3.9 is now rescheduled to enter testing on July 20th.

- Now since you are running testing, and since XYZ-3.7 is buggy, you could probably use XYZ only after July 20th. That is you essentially ended up with a broken XYZ for about one month.

The situation can get much more complicated, if say, XYZ depends on 4 other packages. This could in turn lead to unusable testing distribution for months. The above scenario which is artificially created by me, can occur in the real life. But such occurrences are rare.

### 3.1.8 From an administrator's point of view, Which distribution requires more attention?

One of the main reasons many people chose Debian over other Linux distributions is that it requires very little administration. People want a system that just works. In general one can say that, stable requires very little maintenance while testing and unstable require constant maintenance from the administrator. If you are running stable, all you need to worry about is, keeping track of security updates. If you are running either testing or unstable it is a good idea to be aware of the new bugs discovered in the installed packages, new bugfixes/features introduced etc.

### 3.1.9 What happens when a new release is made?

This question will not help you in choosing a Debian distribution. But sooner or later you will face this question.

The stable distribution is currently etch; The next stable distribution will be called as lenny. Let's consider the particular case as to what happens when lenny is released as the new stable version.

- oldstable = sarge; stable = etch; testing = lenny; unstable = sid

- Unstable is always referred to as sid irrespective of whether a release is made or not.

- packages constantly migrate from sid to testing (i.e. lenny). But packages in stable (i.e. etch) remain the same except for security updates.

- after sometime testing becomes frozen. But it will still be called testing. At this point no new packages from unstable can migrate to testing unless they include release-critical (RC) bug fixes.

- When testing is frozen, all the new bugfixes introduced, have to be manualy checked by the members of the release team. This is done to ensure that there wont be any unknown severe problems in the frozen testing.

- RC bugs in 'frozen testing' are reduced to zero.

- The 'frozen testing' with no rc-bugs will be released as the new stable version. In our example, this new stable release will be called as lenny.

- At this stage oldstable = etch, stable = lenny. The contents of stable and 'frozen testing' are same at this point.

- A new testing is forked from the current stable.

- Packages start coming down from sid to testing and the Debian community will be working towards making the next stable release.

### 3.1.10 I have a working Desktop/cluster with Debian installed. How do I know which distribution I am running?

In most situations it is very easy to figure this out. Take a look at the `/etc/apt/sources.list` file. There will be an entry similar to this:

         deb http://ftp.us.debian.org/debian/ unstable main contrib

The third field ('unstable' in the above example) indicates the Debian distribution the system is currently tracking.

You can also use `lsb_release` (available in the `lsb-release` package). If you run this program in an unstable system you will get:

         $ lsb_release  -a
         LSB Version:    core-2.0-noarch:core-3.0-noarch:core-3.1-noarch:core-2.0-ia32:core-3.0-ia32:core-3.1-ia32
         Distributor ID: Debian
         Description:    Debian GNU/Linux unstable (sid)
         Release:    unstable
         Codename:   sid

However, this is always not that easy. Some systems might have `sources.list` files with multiple entries corresponding to different distributions. This could happen if the administrator is tracking different packages from different Debian distributions. This is frequently referred to as apt-pinning. These systems might run a mixture of distributions.

### 3.1.11 I am currently tracking stable. Can I change to testing or unstable? If so, How?

If you are currently running stable, then in the `/etc/apt/sources.list` file the third field will be either etch or stable. You need to change this to the distribution you want to run. If you want to run testing, then change the third field of `/etc/apt/sources.list` to testing. If you want to run unstable, then change the third field to unstable.

Currently testing is called lenny. So, if you change the third field of `/etc/apt/sources.list` to lenny, then also you will be running testing. But when lenny becomes stable, you will still be tracking lenny.

Unstable is always called Sid. So if you change the third field of `/etc/apt/sources.list` to sid, then you will be tracking unstable.

Currently Debian offers security updates for testing but not for unstable, as fixes in unstable are directly made to the main archive. So if you are running unstable make sure that you remove the lines relating to security updates in `/etc/apt/sources.list`.

If there is a release notes document available for the distribution you are upgrading to (even though it has not yet been released) it would be wise to review it, as it might provide information on how you should upgrade to it.

Nevertheless, once you make the above changes, you can run `aptitude update` and then install the packages that you want. Notice that installing a package from a different distribution might automatically upgrade half of your system. If you install individual packages you will end up with a system running mixed distributions.

It might be best in some situations to just fully upgrade to the new distribution running `apt-get dist-upgrade`, `aptitude safe-upgrade` or `aptitude full-upgrade`. Read apt's and aptitude's manual pages for more information.

### 3.1.12 I am currently tracking testing (lenny). What will happen when a release is made? Will I still be tracking testing or will my machine be running the new stable distribution?

It depends on the entries in the `/etc/apt/sources.list` file. If you are currently tracking testing, these entries are similar to either:

         deb http://ftp.us.debian.org/debian/ testing main

or

         deb http://ftp.us.debian.org/debian/ lenny main

If the third field in `/etc/apt/sources.list` is 'testing' then you will be tracking testing even after a release is made. So after lenny is released, you will be running a new Debian distribution which will have a different codename. Changes might not be apparent at first but will be evident as soon as new packages from unstable go over to the testing distribution.

But if the third field contains 'lenny' then you will be tracking stable (since lenny will then be the new stable distribution).

### 3.1.13 I am still confused. What did you say I should install?

If unsure, the best bet would be stable distribution.

## 3.2 But what about Knoppix, Linex, Ubuntu, and others?

They are not Debian; they are Debian based. Though there are many similarities and commonalities between them, there are also crucial differences.

All these distributions have their own merits and are suited to some specific set of users. For more information, read the information of `software distributions based on Debian` available at the Debian website.

### 3.2.1 I know that Knoppix/Linex/Ubuntu/... is Debian-based. So after installing it on the hard disk, can I use 'apt' package tools on it?

These distributions are Debian based. But they are not Debian. You will be still able to use apt package tools by pointing the `/etc/apt/sources.list` file to these distributions' repositories. But then you are not running Debian, you are running a different distribution. They are not the same.

In most situations if you stick with one distribution you should use that and not mix packages from other distributions. Many common breakages arise due to people running a distribution and trying to install Debian packages from other distributions. The fact that they use the same formatting and name (.deb) does not make them inmediately compatible.

For example, Knoppix is a Linux distribution designed to be booted as a live CD where as Debian is designed to be installed on hard-disk. Knoppix is great if you want to know whether a particular hardware works, or if you want to experience how a linux system 'feels' etc., Knoppix is good for demonstration purposes while Debian is designed to run 24/7. Moreover the number of packages available, the number of architectures supported by Debian are far more greater than that of Knoppix.

If you want Debian, it is best to install Debian from the get-go. Although it is possible to install Debian through other distributions, such as Knoppix, the procedure calls for expertise. If you are reading this FAQ, I would assume that you are new to both Debian and Knoppix. In that case, save yourself a lot of trouble later and install Debian right at the beginning.

### 3.2.2 I installed Knoppix/Linex/Ubuntu/... on my hard disk. Now I have a problem. What should I do?

You are advised not to use the Debian forums (either mailing lists or IRC) for help as people might advise you thinking that you are running a Debian system and the "fixes" they provide might not be suited to what you are running. They might even worsen the problem you are facing.

Use the forums of the specific distribution you are using first. If you do not get help or the help you get does not fix your problem you might want to try asking in Debian forums, but keep the advise of the previous paragraph in mind.

### 3.2.3 I'm using Knoppix/Linex/Ubuntu/... and now I want to use Debian. How do I migrate?

Consider the change from a Debian-based distribution to Debian just like a change from one operating system to another one. You should make a backup of all your date and reinstall the operating system from scratch. You should not attempt to "upgrade" to Debian using the package management tools as you might end up with an unusable system.

If all your user data (i.e. your `/home`) is under a separate partition migrating to Debian is actually quite simple, you just have to tell the installation system to mount (but not reformat) that partition when reinstalling. Making backups of your data, as well as your previous system's configuration (i.e. `/etc/` and, maybe, `/var/`) is still encouraged.

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The Debian GNU/Linux FAQ