Updated: March 26, 2025
Here's a wee issue you won't come across every day. Or even every week. Say you're using Linux. A Plasma desktop, to be more precise. Let's say Kubuntu. There, the default file manager is a program called Dolphin, and it's extremely capable. It can do many wondrous things. It can extract archives in various formats, like say tar, zip, and others. But most of the time, it must rely on what your system has. For instance, it won't do 7z natively, unless you add a package.
I encountered a problem with a rar file extraction recently. The funny thing is, the error message is quite weird, and does not indicate you have an issue with the file format. Instead, you will get a "bogus" message that your system does not have enough free space available. At this point, you might start sweating and fretting. No need, let's fix this.
Add some rar-ity into your Linux
By default, Ubuntu-based distros, Kubuntu included, which is my operating system of choice, does not have the rar utilities (either rar or unrar) installed. This means the file manager cannot create or extract archives of this type. The only problem is, the error is wrong. It should simply say: unsupported format, please grab the necessary components, yo.
Hit the command line, and type:
sudo apt install unrar
Optionally, grab also the rar package, so you can create rar archives, too:
sudo apt install rar
Just to be on the safe side, check you truly don't have a space problem:
df -lh
Filesystem Size Used Avail Use% Mounted on
tmpfs 1,6G 1,8M
1,6G 1% /run
/dev/dm-0 454G 37G 394G 9% /
...
Verify that the utility works as it should:
unrar x "filename"
Now, go back to Dolphin, right-click, extract, and everything will be fine.
Conclusion
Yes, there you go. Dolphin be lovely, mighty and powerful, but it does not handle errors that well. Ideally, the file manager could allow you to grab additional handlers for various file types on the fly, but this would break the package management mechanisms, and might be something of a security risk for impetuous people. At the very least, Dolphin could provide more meaningful, more graceful messages on errors.
Rar isn't exactly the most used file format today. But once, it was quite popular. Indeed, I happen to have a bunch of old games saved in rar archives. Well, just recently, I grabbed my ancient Max Payne game, which I've saved as a rar some twenty years ago. It's a very neat, compact game, and all its files fit nicely into a single package. So you can just extract it, and you're good to go. No fancy installation - well apart from the first one, that is. Technically, I could just repackage everything as zip or 7z, but I would still need to handle rar in some way. Hence, the problem. Hence, this tutorial. And that's it.
Cheers.