23 Facts About GNU Emacs

GNU Emacs has been a central component of the GNU project and a flagship project of the free software movement.

In 1976, Stallman wrote the first Emacs, and in 1984, began work on GNU Emacs, to produce a free software alternative to the proprietary Gosling Emacs.

GNU Emacs was initially based on Gosling Emacs, but Stallman's replacement of its Mocklisp interpreter with a true Lisp interpreter required that nearly all of its code be rewritten.

GNU Emacs is written in C and provides Emacs Lisp, implemented in C, as an extension language.

Older versions of the GNU Emacs documentation appeared under an ad-hoc license that required the inclusion of certain text in any modified copy.

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In 2011, it was noticed that GNU Emacs had been accidentally releasing some binaries without corresponding source code for two years, in opposition to the intended spirit of the GPL.

GNU Emacs can be configured to save the list of open buffers on exit, and reopen this list when it is restarted.

Some notifications are displayed briefly in the minibuffer, and GNU Emacs provides a buffer that keeps a history of the most recent notifications of this type.

Buffers which GNU Emacs creates on its own are typically named with asterisks on each end, to distinguish from user buffers.

Each GNU Emacs window has a status bar called the "mode line" displayed by default at the bottom edge of the window.

GNU Emacs windows are available both in text-terminal and graphical modes and allow more than one buffer, or several parts of a buffer, to be displayed at once.

GNU Emacs windows are tiled and cannot appear "above" or "below" their companions.

GNU Emacs will start up, execute the passed-in file or function, print the results, then exit.

An electronic copy of the GNU Emacs Manual, written by Richard Stallman, is bundled with GNU Emacs and can be viewed with the built-in info browser.

GNU Emacs has support for many alphabets, scripts, writing systems, and cultural conventions and provides spell-checking for many languages by calling external programs such as ispell.

GNU Emacs uses UTF-8 for its encoding as of GNU 23, while prior versions used their own encoding internally and performed conversion upon load and save.

Behavior of GNU Emacs can be modified and extended almost without limit by incorporating Emacs Lisp programs that define new commands, new buffer modes, new keymaps, add command-line options, and so on.

GNU Emacs often ran noticeably slower than rival text editors on the systems in which it was first implemented, because the loading and interpreting of its Lisp-based code incurs a performance overhead.

GNU Emacs compiled on a 64-bit machine can handle much larger buffers.

GNU Emacs is one of the most-ported non-trivial computer programs and runs on a wide variety of operating systems, including DOS, Windows and OpenVMS.

Lucid Emacs, based on an early version of GNU Emacs 19, was developed beginning in 1991 by Jamie Zawinski and others at Lucid Inc One of the best-known forks in free software development occurred when the codebases of the two Emacs versions diverged and the separate development teams ceased efforts to merge them back into a single program.

XGNU Emacs development has slowed, with the most recent stable version 21.

Changes in each GNU Emacs release are listed in a NEWS file distributed with GNU Emacs.