There’s no one “proper” way. Running multiple DEs shouldn’t break anything, but each DE comes with it’s own set of dependencies and other software, so it does add clutter. There will also be considerable overlap with config files, so if you change a setting in one DE, it could change settings when using another DE.

Having a separate user account per DE will prevent most of the configuration overlap, but it doesn’t solve the abundance of packages you’ll have installed from having multiple DEs. I don’t think there’s a great “clean” way to do it.

One thing I love about Linux though, is how relatively flexible the user home directory is. When moving to a new distro or PC, usually everything you need to copy over is within your home directory. For what you’re trying to do, I’d consider throwing /home on a separate partition. That way, you can try out multiple DEs and distros, without blowing away your home folder. And you’d be surprised at how small your root partition can be, the vast majority of your storage should likely be reserved for /home. The Steam Deck, for example, uses a root partition that is only 5 gb. On a typical Linux system, I’ve found 64 gb to be plenty for root.

When switching distros and/or DEs, consider cleaning out various config files in your home folder. Almost all of them will be hidden files that have a filename that begins with a period. I only keep specific config files for programs I want to retain data for, like Google Chrome (.config/google-chrome), Thunderbird (.thunderbird), and Steam (.local/share/Steam). If you use SSH keys you’ll want to keep your .ssh folder too. But deleting all other config files will give you a pretty clean start when changing DEs.

I’m an ultra-noob, so those who know more please correct me.

I’m playing with Linux VMs and recently I installed Debian to check it out. When it asked what DE I wanted, I chose all of them :).

The only hard conflict (AFAIK) is the [compontent / feature responsible for loging in] (I don’t know the technical term). Because each DE comes with a different one, you need to choose one.

What I found very confusing in practice is that I could see some DE apps and configuration settings from other DEs. So, unless you know what belongs to what, it’s a bit of a mess (in my VERY limited experience).

I think usually if you use 1 DE per user, it works out fine.

Gnome developers had the genius idea that a session cannot be locked when GDM is not the login manager, so using GDM is basically a requirement for real-world scenarios outside VMs.

Often distributions have some sort of meta package that installs everything related to that desktop, including many applications. Better install the session package and the file manager package and go from there.

I havent tried this out myself by I’ve been told using another user for a DE would work. KDE Plasma is the worst offender for leakage into other DEs, but I love kde’s system applications. Using a window manager or xfce have been fond to run along side kde imo. Mixing gnome forks isn’t a good idea tho

Brings back memories.

My last experiment with that was a few years ago and I thank the creator of debfoster for the help to clean the house up after.

Unless things have changed and you run perhaps a fully containerized system or mannually install just the DE without any bundled SW, you’ll face DE seepage. KDE will throw new programs into the user space that will show on GNOME, getting a windows manager will probably throw conky into the system, Cinnamon will throw a few other things into the pile, and so and so forth.

My personal experience taught me that the system loads those resources for any user to access at will.

If you are looking to evaluate which DE will be the better fit for you, I’d advise trying one by one for at least a week or go for live mediums.

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I haven’t had much issue installing multiple.

The biggest problem I’ve had is if you then want to uninstall one. Usually have to start over.

Something like nixos might be able to handle that much better.

I have kind of messed some things up by installing KDE on my Fedora that already has Gnome. This was almost a year ago, now. I would not advise doing this. It is a bigger hassle than it was worth, and I’m just looking forward to a free moment when I can wipe and clean install.

Your DM should be able to handle multiple DEs just install from command line and pick which DE you want from the DM.