Is there a way to have a common
init.el for several system users?
/etc/emacs.d/init.el for example?
This is documented in chapter 49.4 The Emacs Initialization File of the Emacs manual (which is also included as part of Emacs, use
C-h i to open the info browser which will show you this and many other manuals already on your computer). In short, Emacs loads both
defaults.el in addition to your own startup file, and these two files may be located anywhere in the
load-path. Exactly what directories end up in your
load-path may vary across operating systems and distributions, but in most Linux distributions it will include a directory like