20 ways to break Linux

Linux is a robust OS but there are still lots of ways you can trash it

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Linux has a reputation for robustness but there are still plenty of ways to damage a perfectly working system.

Here we share some of the ways you can trash Linux so you don't make the same mistakes we did.

01. Fill a filesystem

If the filesystem containing /var fills up, nothing can write its log messages and all sorts of system processes may stall. This can be caused by a runaway process spamming /var/log or, if everything is on the same filesystem, it could be all the downloads in your home directory.

02. Reinstall Windows

No, this isn't a typical Linux user's anti-Microsoft jibe - the Windows installer doesn't allow for foreign operating systems or bootloaders, so if you reinstall Windows it will overwrite your bootloader. There's no need to reinstall Linux, though: the installer CD usually has an option to fix the bootloader, or you can run grub-install from a live CD.

03. Run out of memory

4GB of memory may seem like a lot, until you do something daft like running gimp *.jpg in a directory full of 12 megapixel photos (don't ask how we know this). Swap memory will help here, but it will run so slowly you will think the thing has crashed, which it may well do when you use up all the swap too.

04. Follow instructions on the web

Web forums are full of useful hints, tips and commands, but there are also some that will do serious damage. The difficulty lies in telling them apart, dangerous advice may have been given with the best of intentions, or be good advice mis-typed. Be especially cautious of anything that uses su or sudo.

05. Install more Linux

This is rather like the reinstall Windows situation. While distro installers do a good job of detecting Windows and setting up a dual boot, some still do not notice other Linux distros on your disk, so your existing distro may disappear from the bootloader, although the distro itself is still there.

06. Update infrequently

Leaving an installation untouched for many months and then installing 300+ updates in one go isn't necessarily going to break anything, but if it does break - good luck in finding the culprit. Little and often is the safest way to keep a system up-to-date.

07. Update blindly

Never check the list of packages to be installed by a system update, that way you'll have no idea what has gone wrong when it does. Alternatively, use your package manager to produce a list of installed software, so you can see what's changed when things go awry - or check the package manager's log file.

08. Run bleeding edge software

Yes, we all like to try the newest stuff at times, but be aware of the risks. New software has had less testing - that is now your job - so don't upgrade to the latest alpha release when you really need your computer to keep working.

09. Wipe /home

This won't break Linux, but you will lose all of your settings and any personal files stored in there. That's why it is a good idea to keep /home on a separate partition, so you can install and upgrade without messing up your settings and data.

10. Lose a password

Losing your user password stops you doing anything, unless you have automatic logins set up. Losing your root password means you can use the computer, but you cannot install or update software, or make any other system changes. Losing the password for an encrypted filesystem means you may as well go back to pencil and paper.

11. Install a new kernel

This seems odd at first, a new kernel should be better and more secure. But some devices rely on modules that are not supplied with the kernel, especially graphics cards and wireless networking. Some distros will reinstall these automatically, otherwise you need to use a wired network, or reboot with your old kernel, and reinstall the drivers for whatever doesn't work.

12. Try to use pulseaudio

If you've ever been bitten by the complexity of the Linux sound systems, you'll know exactly what this means. Otherwise, don't worry about it. Your sound system will keep working right up until it mysteriously stops. Please can we have a clear, simple and understandable sound system for Linux, preferably one with less layers than an onion?

13. Install packages from another distros

Sometimes your distro doesn't have the package you want, but another one does. Don't be tempted to install a "foreign" package, that's the start of the road to insanity. You may get away with using the odd Debian package on Ubuntu, but sooner or later (and it's far more likely to be sooner where RPM packages are involved) you will get hurt.

14. Run a fork bomb

A fork bomb is a tiny shell script that rapidly creates as many processes as it can until the computer grinds to a halt and the only solution is to power off. Some distros are set up to prevent its effects by limiting the number of processes a single user, even root, can run. If you fancy trying it, here's the code

#!/bin/sh
:(){ :|:& };:

15. Reinstall it

The preferred "solution" to many Windows problems is to reinstall the OS. Do this on Linux and all you achieve is the loss of your settings and customised setup and any chance of discovering the cause of - and solution - to the problem. Reinstalling individual packages rarely helps either, since such an action doesn't touch any settings in your home directory, the most likely source of the problem.

16. Disable swap

You may think that with a minimum of 2-4GB typically fitted to even laptops these days, swap is an anachronism, but some processes expect some of their code to be swapped out. Even if you don't think you need it, it is possible to inadvertently use up lots of memory quickly, so having some swap available is still a good idea, after all, disk space is even more plentiful than RAM.

17. Install from source

If you want the latest version of some obscure (or just brand new) program, sometimes installing from source is the only option. While this is usually fine, you could end up with different versions of the same library in /usr/lib and /usr/local/lib, with effects that are best described as "interesting".

18. Lose it

Linux is appearing on devices that are ever smaller, more convenient, more powerful, and easier to lose. As tempting as it is to store all the details of your life on a netbook, or even a smartphone, consider the consequences of a loss (or "assisted loss") of said device. Such an event won't actually break the device, but its new "owner" will have full access to it and your data, so be careful.

19. Treat it like Windows

Linux and Windows both provide desktop operating systems with a superficial similarity, but they are completely different. Treating a Linux system like Windows is one of the most common causes of breakage among new users. If you are new to Linux, no matter how much experience you have with Windows, don't be ashamed to ask for advice.

20. Spill coffee on it

It really is lamentable that a system so suited for the hacker and programmer can still be rendered useless when it comes in contact with essential programming fuel. Mice and pizzas don't go well together either, although hardcore Linux users probably wouldn't miss the mouse as much as the pizza.

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First published in Linux Format Issue 147

Liked this? Then check out 24 things we'd change about Linux

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