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There are 10 mistakes that you'll 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. Advanced Linux users won't easily get into trouble, not even in the danger zone. And when they do get into trouble, they can help themselves...
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 fighter jet:
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.
Contents of this page:
- 1. Be very careful with external repositories (like PPA's) and with external .deb files
- 2. Be restrictive with root authority (administrative permissions)
- 3. Be careful with add-ons, extensions, applets and desklets
- 4. Never use cleaning or defrag applications
- 5. Don't mix desktop environments
- 6. Never use installation scripts like Ultamatix, Ubuntu Tweak, Ubuntu Sources List Generator, Ubuntuzilla and UKUU
- 7. Don't use Grub Customizer
- 8. Don't enable the software repository "romeo"
- 9. Never remove any application that's part of the default installation of Ubuntu or Linux Mint
- 10. Don't experiment on a production machine
- 11. Want more tips?
Be very careful with external repositories (like PPA's) and with external .deb files1. Software from third-party repositories (like PPA's) and external .deb installers, is untested and unverified. Therefore it may damage the stability, the reliability and even the security of your system. It might even contain malware....
Furthermore, you make yourself dependent on the owner of the external repository, often only one person, who isn't being checked at all. By adding a PPA to your sources list, you give the owner of that PPA in principle full power over your system!
Therefore only use a PPA when you really (really!) have no acceptable alternative. Or when you're a tester for a particular piece of software (which you should only be doing on a non-essential test computer).
PPA's are a mixed blessing, to say the least. If used wisely and very restrictively, PPA's can occasionally be of great help. But used carelessly, they're for Linux what the bubonic plague was for the Middle Ages....
Have you already enabled PPA's or other third-party repo's and do you want to get rid of them? Then you can recreate a clean software sources list like this.
For the same reasons you also need to be careful with .deb files from external sources:
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 gnome-look.org.
Be restrictive with root authority (administrative permissions)2. A root desktop would defeat the security model that's been in place for Ubuntu and Mint since their inception. Therefore, even the administrator logs in with mere user permissions.
Applications are meant to be run with non-administrative user permissions (or as mere mortals), so you have to elevate their privileges to modify the underlying system.
For example, you wouldn't want that recent crash of VLC to wipe out your entire /usr directory due to a bug. Or that vulnerability that was just posted in LibreOffice, to allow an attacker to gain a root shell. Or that malicious script on a website, to take over your entire system by means of an (as yet) unpatched Firefox or Adobe Flash Player. Et cetera, et cetera....
It's just good practice on any operating system, in fact the only sane practice, to run your applications on a user level. Only administrative tasks should be executed with root permissions, on a per-need basis.
Only use sudo, pkexec and admin:// when absolutely necessary2.1. With sudo, pkexec and admin:// you give yourself root permissions (administrator power). You should only do that for system administration applications and never for ordinary applications.
Unnecessary use of sudo (and pkexec and admin://) can mess up your file and directory permissions, causing all kinds of weird malfunctions.
When you launch an ordinary application with sudo, that application creates files and directories that are the property of root, and not of you. Plus it changes the ownership of some existing files to root.
Never launch ordinary applications with sudo (or pkexec or admin://). It's unnecessary, it's dangerous and you run a big risk of messing up the permissions of your own files.
Be careful with add-ons, extensions, applets and desklets3. Be careful with the add-ons, extensions, applets and desklets that you install. Because some of them can cause lots of problems:
Firefox and Chromium/Chrome add-ons and extensions: don't trust them blindly3.1. 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 your browser becomes. Furthermore, some add-ons may cause malfunctions in other add-ons, or even in the browser itself.
Have you already become the victim of such an add-on? Then cleanse your web browser like this (item 10).
Desklets and applets: think before you install3.2. Applets and desklets can beautify your desktop and even add useful features. But they can cause problems. So keep their number down.
The more desklets and applets you install, the slower your system becomes. What's more, some of them may cause malfunctions in each other or in the desktop itself.
Never use cleaning or defrag applications4. With cleaning applications like BleachBit or deborphan, you easily destroy more than you want. They're software wrecking balls that can damage your system beyond repair.
You can't trust them, because unless you're very careful, they remove too much and damage the system. Sometimes so heavily, that your Mint can't boot into the desktop anymore. Under certain circumstances, BleachBit can even pollute your system with massive amounts of junk.
BleachBit, deborphan and others like them are superfluous at best, and disastrous at their worst. They're "tools" that primarily cater to the psychological needs of new Linux users who come fresh from Windows, and mistakenly assume that certain essential Windows maintenance is needed on Linux as well.
In short: it's a newbie trap. Don't fall for it.
Besides, cleaning applications are superfluous. Linux hardly experiences any pollution. So cleaning is not necessary. You may at most win a gigabyte or so of disk space, at an unacceptably high risk of damage. Should you wish to clean up a bit anyway, then this is a safe way for Linux Mint.
There's only one exception: you'll want to reduce the number of old kernels from time to time. This is how to do that (item 9).
Defragmentation tools are even worse. Unfortunately, you can find some defrag tools in the "fringes" of the Linux ecosystem.... Don't use them! There's a considerable risk that they either mess up your system beyond all repair, or cause massive loss of files.
Defrag tools are dangerous rubbish. Without any exception. What's more: Linux doesn't even need defragmentation.
Don't mix desktop environments5. Using different desktops on the same system, can lead to strange problems and errors. Installing another desktop can change system files and dependencies, alter default system and application settings and create incompatibilities.
This is why there are different editions of Mint, rather than a single one (size issues aside).
Especially the mix of KDE with other desktops is toxic. A Linux Mint in which you install the full KDE desktop alongside the existing other desktop environment (MATE, Cinnamon or Xfce), becomes a hopelessly polluted mess. This pollution (extra libraries, system files etc.) will decrease performance and may cause instability and malfunctions.
If you want to ensure that your operating system continues to work well, stick to the default desktop environment. And don't install any KDE applications in Linux Mint, 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.
There are desktop environments that share a lot of system files and libraries "under the hood"; it's less problematic to install those alongside each other. For example: Xfce doesn't fit too badly alongside the Cinnamon or MATE of Linux Mint.
But even then some pollution is inevitable... A system with a single desktop will always perform best.
Have you made this mistake and do you wish to undo it? Then the best approach is unfortunately a clean re-installation.
Don't install a second full-blown file manager5.1. Related to the "don't mix desktop environments" issue: completely replacing your default file manager by another, will almost certainly lead to a disastrous mess: the removal of the default file manager might even make your desktop unusable.
It's not even advisable to install a full-blown second file manager next to your default one. It's best to stick to the file manager that comes by default with your desktop environment, and leave it at that.
The reason is, that full-blown file managers are deeply interwoven with the desktop environment for which they were designed. They're the backbone of the desktop. That means that they can cause problems after installation in a "foreign" desktop environment: they simply engrain themselves too deeply in that "foreign" desktop and tend to clash sometimes with its primary file manager.
Exceptions are stand-alone simple file managers like Double Commander and Midnight Commander. They don't interweave themselves with the desktop environment at all, and only do their primary limited task: basic file management.
Never use installation scripts like Ultamatix, Ubuntu Tweak, Ubuntu Sources List Generator, Ubuntuzilla and UKUU6. 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!): Ultamatix6.1. Ultamatix is the worst of the bunch. It will irreparably damage your system.
Note: this horrible project seems to be dead, but it has been resurrected from the grave before... So for the time being I won't remove this warning.
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 Linux Mint 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 Generator6.2. There's also an "orange alert" (high danger) category, which contains the applications Ubuntu Tweak and Ubuntu Sources List Generator.
Ubuntu Tweak and Ubuntu Sources List Generator are dangerous as well. 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 operating system version or what they'll do to your system. Very risky indeed. Better stay away from them...
Elevated danger level (yellow alert): Ubuntuzilla and UKUU6.3. Ubuntuzilla and UKUU (Ubuntu Kernel Update Utility) are more limited in scope, and pose no security risk. But you'd better avoid them as well:
Ubuntuzilla6.3.1. Ubuntuzilla 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 Mint version.
With Ubuntuzilla, you bypass the entire system of tweaks and quality checks that the Ubuntu and Mint developers apply to Firefox.... This endangers the stability and reliability of Firefox.
UKUU (Ubuntu Kernel Update Utility)6.3.2. UKUU (Ubuntu Kernel Update Utility) is intended for one goal only: testing new mainline kernels. So far, so good. But don't abuse it: the mainline kernels it offers are not supported by Mint or Ubuntu, and are not appropriate for everyday use.
UKUU's mainline kernels aren't reliable enough for normal use. Furthermore: as these are pure upstream kernels (built using Ubuntu kernel configuration files), they do not include any Ubuntu/Mint-specific drivers or patches, nor any proprietary modules or restricted binary drivers.
Even if you know how to boot from an older kernel in case of kernel failure: you risk losing important work because of an unstable and unreliable kernel. Even worse things may happen: for example, certain mainline kernels of the 4.18 series corrupted EXT4 filesystems, which caused irrecoverable data loss.
Don't use Grub Customizer7. There's also a third-party tool called Grub Customizer, which massively complicates your bootloader. It heavily changes the contents of the system folder /etc/grub.d, which is where important parts of Grub reside. These changes don't disappear, when you remove Grub Customizer after using it!
In that system folder, Grub Customizer changes files into so-called "proxified" files, which creates a complex and unclear situation. This additional thick layer of complexity may have something to do with the problems it can cause: the more you complicate something, the bigger the risk of failures....
Another negative indication is that Grub Customizer isn't present in the official software sources.
The main problem with Grub Customizer in a nutshell: as long as it works as expected, all is fine.
But when there is a problem with it, removing Grub Customizer and trying to boot without it can create big difficulties. Because the program has done major changes in /etc/grub.d, which would all have to be undone manually. For uninstalling Grub Customizer after using it, does not remove its changes.
That's the downside of the complexity it adds. And for what? For a few things, most of which are non-essential, that can usually also be done without adding a thick layer of complexity....
Grub Customizer (grub-customizer) may look easy and nifty, but can mess up a vital part of your operating system. Your bootloader is as vital as it gets: after all, a system that won't boot anymore, is useless.
Furthermore, most of what Grub Customizer does can also be achieved by other means, without adding thick layers of complexity "under the hood".
Thankfully, Grub Customizer isn't present in the official software repositories. Let's hope it stays out.
If you would like to know more about this: a more detailed analysis of what Grub Customizer does, and how you can (hopefully) undo the complexity it has caused, can be found on this page (with screenshots).
Don't enable the software repository "romeo"8. Don't enable the software repository "romeo", unless you're a tester and don't value a stable system. The full name of this repo in Linux Mint is "Unstable packages (romeo)".
The source "romeo" is very dangerous. It contains unstable and buggy software that hasn't been improved and tested enough yet. Like the comparable source "Proposed" in Ubuntu, which is equally risky. Stay away from it!
When you do enable this source, your system will definitely become unstable sooner or later. The only solution then, is a complete clean re-installation of Linux Mint. With previous formatting of the root partition.
It's disabled by default of course, but like this you can check whether this source is really safely disabled in your system:
Menu button - Administration - Update Manager
Panel: Edit - Software sources
Optional components: Unstable packages (romeo) should be disabled.
The only reason for the existence of the source romeo, is use by testers. Those testers help to hunt for bugs in potential updates, before those updates are being delivered to the users of Linux Mint.
Never remove any application that's part of the default installation of Ubuntu or Linux Mint9. 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 or Linux Mint. Applications that you've added yourself, can be removed safely.
Don't experiment on a production machine10. 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 (enterprise-grade). All Linux Mint versions are LTS nowadays, so with Mint you're always OK.
When you want to upgrade a production machine that's already running on an Ubuntu 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 Ubuntu 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 of Ubuntu (all current and future versions of Linux Mint are and will be LTS);
- on the play boxes you can 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 versions of Ubuntu or Linux Mint.
Want more tips?11. Do you want more tips and tweaks? There's a lot more of them on this website!
Speed up your Linux Mint!
Clean your Linux Mint safely
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