How to uninstall unused window managers and related packages?

Question

I have uninstalled most unused session managers, but there are a few that still show among the options at login. The full list is:

• Gnome classic
• Gnome classic (No effects)        [keep!]
• Gnome/Openbox
• Openbox        [keep!]
• Ubuntu
• Ubuntu 2D

If, as indicated above, I want to keep only "Gnome classic (No effects)" and "Openbox", what installed packages can I remove with apt-get?

Also, supposing that removing those packages does not yet eliminate all the unwanted options from the list above (e.g. maybe they are included in the same Debian package that includes one of the wanted options), is there a way to at least remove them from the options list?

Lastly, I see, from, for example, dpkg-show -l | grep ii | grep -i xfce, that I may still have remnants lying around from formerly installed session managers, even though they no longer show up among the options at login. (They persist, BTW, even after sudo apt-get -y autoremove.) How can I find what all those remaining packages are so that I can delete them?

EDIT: Whatever you do, do not run sudo apt-get remove unity*, or anything similar. If you want to uninstall unity, see here.

Solution

To remove ubuntu sudo apt-get remove unity* I don't think you can remove gnome classic with effects and keep it without.

You can remove them from the login screen by deleting the file at /usr/share/xsessions/

Comments

[kjo]

I'm a bit queasy about that wild-card expression "unity*". For one thing, won't the shell expand it? And, even if I quote it, how can I find out what it will match before I run the command for real?

[Pieter Vandamme]

you can do sudo apt-get remove unity and press tab twice to see what you'll delete

[kjo]

I upvoted your answer too quickly; it really deserves a downvote; there are so many things wrong with I don't know where to begin; first the wildcard in sudo apt-get remove unity* will get interpreted by the shell, not by apt-get; second, even if you quoted it, it is not what you think it is: apt-get interprets it as a regular expression; it will match not only strings beginning with "unity", but also strings like "mainunit-0.1.2"...

[kjo]

..., and if that weren't bad enough, third even if one used the regular expression corresponding to that shell glob, the resulting command sudo apt-get '^unity.* would delete unity-greeter, and when logged out would see a "running in low-graphics mode" dialog... sheesh