How I can hide a user from the login screen?

I have Kubuntu 9.04 and I want to hide a user from appearing in the Login Screen, I shouldn't remove it permanently of course, but I need to make it visible again when needed.

2 Answers

System Settings > Advanced > System > Login Manager > Users

Select the check-boxes of the users you want to hide.

In Debian-based systems (which includes Ubuntu and Kubuntu, both versions new and old), any user with a UID less than 1000 will not show up as a user you can log in with, but you can still use the user from the command line with things such as ssh and ftp.

So to make the user bob disappear from the login screen, run the following command (800 can be any value less than 1000, but I like starting in that range):

$ sudo usermod -u 800 bob