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Avoid 10 fatal mistakes in Ubuntu

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There are 10 mistakes that you definitely want to avoid, for the sake of the health of your system. Because they may be fatal.

As with all warnings in general, these warnings are especially important for beginners with Linux. Experienced Linux users won't easily get into trouble, even in the danger zone. And they can help themselves, when they do get into trouble...

To make a comparison with jet planes: it all depends on how you want to use your computer.

As a pilot of the trusted F-18:

Or as a test pilot of an experimental plane:

Or as a pilot of... well, whatever it is:

If (for the time being?) the battle proven reliability of the F-18 is what you're looking for, then you can benefit from the warnings below.

Never use installation scripts like Ultamatix, Ubuntu Tweak, Ubuntu Sources List Generator or Ubuntuzilla

1. Third party installation scripts are all dangerous: some are acutely risky, some a little less. But you'd better avoid the lot. Below I'll describe some of the most common dangerous scripts.

Severe danger level (red alert!): Ultamatix

1.1. Ultamatix is the worst of the bunch. It will irreparably damage your system.

Ultamatix installs all kinds of unstable versions of applications (nightly builds). Besides, it makes use of forced permits: --assume-yes and --force-yes are very dangerous. The developer says that those are being used because "he doesn't want to bother the users with all kinds of questions". It takes only one wrong dependency, buggy application or another hitch, and your system may be damaged beyond repair....

When you've already used this script, a clean re-installation of Ubuntu is the only solution. With previous formatting of the root partition.

Furthermore, Ultamatix is essentially superfluous: everything it does, you can do also in the safe official way. With only a little extra effort.

High danger level (orange alert): Ubuntu Tweak and Ubuntu Sources List Generator

1.2. Ubuntu Tweak and Ubuntu Sources List Generator are also dangerous. Don't use them! With them, you can add several PPA's and third party software, without it being clear where everything comes from and without being asked for a verification key.

You can add all kinds of software packages without verification or quality check, and without knowing if they are fit for your Ubuntu version or what they'll do to your system. Very risky indeed. Better stay away from them...

Elevated danger level (yellow alert): Ubuntuzilla

1.3. Ubuntuzilla is more limited in scope, and poses no security risk. But you'd better avoid this one as well. It may cause strange malfunctions in Firefox, because the Ubuntuzilla version of Firefox is "original upstream software" which isn't completely adapted to and tested for your Ubuntu version.

With Ubuntuzilla, you bypass the entire system of tweaks and quality checks that the Ubuntu developers apply to Firefox.... This endangers the stability and reliability of Firefox.

Never use cleaning applications

2. With cleaning applications like Computer Janitor or Bleachbit, you easily destroy more than you want. You can't trust them, because before you know it, they remove too much and damage the system.

Besides, they are useless. Linux hardly experiences any pollution. So cleaning is superfluous. You may at most win a couple of hundreds of megabytes disk space, at an unacceptably high risk of damage. Should you wish to clean up a bit anyway, then this is a safe way.

Be very careful with adding repositories like PPA's to your sources list

3. Software from PPA's (third-party repositories) are untested in your Ubuntu version, and may damage the stability and reliability of your system. Furthermore, you make yourself dependent on the owner of the PPA, often only one person, who isn't being checked...

Therefore only use a PPA when you really (really!) have no acceptable alternative.

Handle with great care: .deb files

4. Files with the extension .deb are separate installers, just like .exe installers for Windows. You can download debs from some websites. When you double-click them, they ask for your password and then they install themselves in your system.

Only install those .deb files that you trust completely. When you're at all unsure about a .deb file, don't install it! These files are unchecked, unverified and may do damage to your system. They may even contain malware, like spyware and such.

This happens in the real world: I know of at least one incident. Some years ago, malware (a trojan) was detected in a .deb file, that was available for download on the much visited website of

Firefox and Chromium/Chrome extensions: don't trust them blindly

5. Firefox add-ons with malicious software: it has happened, in spite of the malware scanning efforts by Mozilla. Don't trust them blindly. This goes for Chromium/Chrome as well.

And keep their number down anyway: don't turn Firefox and Chromium/Chrome into a Christmas tree. The more extensions you install, the slower Firefox and Chromium/Chrome become. Furthermore, some add-ons may cause malfunctions in other add-ons or in the browser itself.

Don't mix desktop environments: choose Ubuntu (Gnome/Unity), Xubuntu (Xfce) or Kubuntu (KDE)

6. An Ubuntu in which both the full Unity/Gnome and the full KDE desktop environments has been installed, turns your system into a hopelessly polluted mess. This pollution will decrease performance and may cause instability and malfunctions.

If you want to ensure that your operating system continues to work well, then you'll install either Ubuntu (Gnome/Unity) or Kubuntu (KDE). And then you won't install any KDE applications in Ubuntu, that upon installation pull in half of the KDE desktop as dependent files (like for example DVD burner K3B does)...

Tip: when you install applications by means of Synaptic Package Manager, then you can check beforehand what a particular application needs as dependent files.

Desktop environments that share a lot "under the hood", you may install alongside each other, if you wish. Xfce (the desktop environment of Xubuntu) fits pretty nicely alongside the Gnome/Unity of Ubuntu. But even then some pollution is inevitable...

Have you made this mistake and do you wish to undo it? Then the best approach is unfortunately a clean re-installation.

(continued in the column on the right)

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Don't turn on the software repository "proposed"

7. Don't turn on the software repositories of "proposed", unless you're a tester and don't value a stable system. Like this you can check whether this source is disabled:

- If not installed yet: first install Synaptic Package Manager by means of the Ubuntu Software Center.

- Click on the grey Ubuntu logo (Dash home).
Query: synaptic
Click on Synaptic Package Manager

Settings - Software Sources - tab Updates

You'll see this unchecked update source:
Pre-released updates (trusty-proposed).

Don't enable it:

The "proposed" source is very dangerous. It contains unstable and buggy software that hasn't been improved and tested enough yet. Stay away from it!

When you do enable this source, the system will definitely become unstable sooner or later. The only solution then, is a complete clean re-installation of Ubuntu. With previous formatting of the root partition.

Handle with some care: the software repositories Backports, Partners and Independent

8. There are three software repositories that are safe enough to enable them in your system, but nevertheless have to be handled with some care: Backports, Partners and Independent.

Definitely not a fatal matter, because these repositories pose an acceptable low risk. But this risk, although low and acceptable, is still worthy of some attention...


8.1. In Ubuntu, the software repository of "backports" is enabled by default. But with a lowered (harmless) priority, so that you can only install software from it when you consciously choose so.

Like this you can check whether this source is enabled:

- If not installed yet: first install Synaptic Package Manager by means of the Ubuntu Software Center.

- Click on the grey Ubuntu logo (Dash home).
Query: synaptic
Click on Synaptic Package Manager

Settings - Software Sources - tab Updates

You'll see this checked update source:
Unsupported updates (trusty-backports).

The "backports" source is much less risky than "proposed", because it holds software that's stable in itself. But this software hasn't been tested for your version of Ubuntu. Therefore it may still diminish the stability of (parts of) the system.

Although this repository has been enabled, it has therefore been issued a low and harmless priority. My advice is: keep backports enabled, but be cautious when using it.

To check the priority of Backports you can run the following command in a terminal:
apt-cache policy | grep backports

Now you'll see that the priority of the Backports repository is pinned to 100 for everything except the translations (in a localized system). Other repositories (and the translations in Backports) have the default priority 500.

This means that you have to explicitly choose to install the backport version of a package, if another version of that package also exists in a non-backports repository. The advantage of this is, that if a package is only available in Backports, you'll be able to install it without modifying anything else.

Partners and Independent

8.2. Like this you can check the current status of the repositories Partners and Independent:

- If not installed yet: first install Synaptic Package Manager by means of the Ubuntu Software Center.

- Click on the grey Ubuntu logo (Dash home).
Query: synaptic
Click on Synaptic Package Manager

Settings - Software Sources - tab "Other Software"

Here you can enable the Partners repository (it's not enabled by default) and the Independent repository. This gives you access to certain software from third parties, such as companies (the partners) that have entered into an agreement with Canonical.

So far, so good. But these repositories may pose a security risk, because they aren't always being updated adequately.... Updates come from the partner companies and independent developers, not from Canonical: Canonical only does the packaging for them. Those partner companies and the independents don't always pay as much attention to providing security updates as they should.

For example, in the past the Partners repository contained an outdated and insecure version of Adobe Flash Player (whereas the regular Multiverse repository contained the secure version, under another name!). Same thing with certain localized versions of Adobe Reader (which is a highly attacked target by malware).

So it's better to use this repositories with some care. By all means do enable them, but don't put too much trust in the security of the software you install from it.

Never remove any application that's part of the default installation of Ubuntu

9. Even when you never use a particular default application: don't remove it. Reason: the default installation is an intertwined system that's dependent on shared supporting files, which makes the operating system run stable.

When you remove a default application, you run a risk of seriously damaging the system. With some default applications this risk is bigger than with others, and with some there's no risk at all. But it's best to avoid this risk altogether.

If you want to, you can remove an unused application from the menu, but don't remove it from the system.

This limitation applies only to those applications, that are part of the default installation of Ubuntu. Applications that you've added yourself, you may remove without problems.

Don't experiment on a production machine

10. Probably not all of your computers are equally important to you. Some computers are real production machines, or "work horses" that you always must be able to rely on. Other computers are more or less like "play boxes"; fun to have, but of no vital importance.

It's important to treat both kinds of computers differently. Do not experiment on a production machine, no matter how tempting it may be to try out something new.

Only do your experiments on the play boxes or on a dedicated testing machine. Because otherwise you may end up suddenly with an unusable computer, and for a production machine that's often a small disaster.

The best approach is, to install only LTS versions of Ubuntu on production machines. Because LTS versions are extra good and reliable.

When you want to upgrade a production machine that's already running on an LTS version, to a newer LTS version, then only do that after the appearance of the first point release ("Service Pack 1") of that newer LTS version.

The best practice is, to split your computer work force in three: work horses, play boxes and testing machines.

- on the work horses you only install LTS versions;

- on the play boxes you install the latest stable Ubuntu every six months;

-  on the testing machines you do your wild experiments, and your bug hunting in alpha and beta editions of the development version of Ubuntu.

Want more?

11. Do you want more tips and tweaks for Ubuntu? There's a lot more of them on this website!

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