This guide is aimed at computer programmers who want to master the GNU Emacs text editor. It has been said that the Emacs learning curve is not so much steep as long. While the initial learning curve is indeed much steeper than other editors, that is a hump you’ll get over fairly soon. This guide does start from the basics, but its real aim is to help you reach the next level —programming the behavior of Emacs itself— in months rather than years. The focus is on self-driven discovery by...