It used to be a prerequisite, editing your XF86Config / xorg.conf file. It was like a test to see if you should be running Linux. Things are so much easier now!
FYI, I found out the hard way that you shouldn't be editing it for most things at all, now. I had a hell of a time trying to figure out how to map my caps lock to control. It is now a gnome setting you fix by running one command:
gsettings set org.gnome.desktop.input-sources xkb-options "['ctrl:nocaps', 'compose:ralt', 'terminate:ctrl_alt_bksp']"
That also sets compose key and termination.