I could not log into my laptop (running on Ubuntu) yesterday. Every time I entered my password — a password I haven’t changed in years — I was returned to the same login screen all over again! But I could log into a console by pressing CTRL+ALT+F1, so it was definitely not a typo-in-the-password error. Since I always have a second user account on my PCs, it was also easy for me to verify that I could log in (in desktop/graphical mode) as a different user without any difficulty.
If, like me, you want to easily have some program start every time you boot up your Linux server, you need to find and edit the
rc.local file in your file-system.
/etc/rc.local is really a simple place to put shell commands and/or scripts you want to run when booting up.