startx is a shell script that that gathers the arguments to finally execute xinit. startx script (in /usr/bin) has the following note: This is just a sample implementation of a slightly less primitive interface than xinit. It looks for user .xinitrc and .xserverrc files, then system xinitrc and xserverrc files, else lets xinit choose its default. The system xinitrc should probably do things like check for .Xresources files and merge them in, start up a window manager, and pop a clock and several xterms. Site administrators are STRONGLY urged to write nicer versions.