An Attempt to Apply Emacs-Keybindings Globally on Linux/X11

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Overview

A small tool that applies Emacs-keybindings on all Linux/X11 applications is provided here. By using this, you can use any applications (e.g., LibreOffice, okular (PDF viewer), and etc.) with Emacs-like keybindings running on Linux

This tool is implemented as a proof-of-concept of an alternative of XKeymacs or emacs.ahk, which are implemented on Win32 and thus lacked on Linux/X11. It is made up of about 1,000 lines of code, and thus relatively easy to hack. (I personally hope that someone builds a more practical and generalized keybinding configuration tool using similar techniques :-)

Running Platform

OpenSUSE 11.4/12.1 + KDE4 (Some modifications might be needed on other Linux distributions/window managers)

Download

x11keymacs.tar.gz (9KB)

License

MIT License

Installation

Simple do "make & make install", and the executable file (x11keymacs) will be installed under /usr/local/bin

$ cd x11keymacs/
$ make
$ sudo make install

Usage (General Information)

In order to run x11keymacs, you need the following previleges:

• Read/Write privileges on /dev/uinput, /dev/input/event*
  • In case /dev/uinput does not exist, you first need to "modprobe uinput" to create this device file
• X-Window server access privileges
  • You need to give X server access privileges to the user that runs this tool, for example using xhost or xauth. It is also needed to provide enviroment variable "DISPLAY" correctly.

By running the following command from the user having the above privileges, keyboard input is converted to Windows-like input from the original Emacs-like keybindings.
(Note that you need to modify the /dev/input/... part to match your keyboard model.)

$ /usr/local/bin/x11keymacs /dev/input/by-id/usb-PFU_Limited_HHKB_Professional_JP-event-kbd &

For instance, Ctrl-P key input is converted to up key, which helps Emacs-users to avoid being frustrated under some "Print" dialog box that has mistakenly popped up.

X11keymacs accepts --exclude filename option for excluding window titles from applying keyboard input conversion using regular expressions. For example, by adding --exclude $HOME/.x11keymacs_exclude to the parameter and by providing the "$HOME/.x11keymacs_exclude" of the following content would exclude Emacs(Gtk+) and VMware Player from the keyboard input conversion targets.

^emacs-gtk@
(^|- )VMware Player$

Example Usage

In my case, I've personally configured to launch this tool on X-server startup. Here's how I have done this:

• First, configure "sudo x11keymacs" to run without password input using "visudo".
  • Example: takeshi ALL=(ALL) ALL, SETENV:NOPASSWD:/usr/local/bin/x11keymacs
• Create a file that lists up window title regexp patterns for windows excluding key conversions.
  (Smple file is provided in tarball as x11keymacs, which excludes Firefox because keysnail addon is preferred on that browser.)
  • Example: cp x11keymacs_excludes $HOME/.x11keymacs_excludes
• Modify $HOME/.xinitrc to execute x11keymacs
  • Example: do cp $HOME/.xinitrc.template $HOME/.xinitrc first, and add the following lines to .xinitrc:

    #
    # Add your own lines here...
    #
    if test -e $HOME/.x11keymacs_excludes; then
        xhost +
        sudo -b DISPLAY="$DISPLAY" /usr/local/bin/x11keymacs \
           --exclude $HOME/.x11keymacs_excludes \
           /dev/input/by-id/usb-PFU_Limited_HHKB_Professional_JP-event-kbd
    fi

The above settings works for me, at least to a level that I can daily use it for my work :-)

Additional Notes

• It is OK to run x11keymacs from terminal, but please be sure to run it as a background process, for example by adding `&' to the end of input, or by using the `-b' option of sudo. Otherwise, your computer would stop acting against any of your keyboard operations.
• In case you're using x11keymacs with any other keyboard configuration mechanism, you need to be aware which key-code translation is applied first. For instance, let's assume that you have configured to swap [CapsLock] and [Control] keys, probably in xorg.conf or somewhere else. Acccording to the order of key-code translation of the two different mechanisms, (A) ctrl-caps swap and (B) xkeymacs, final behavior differs as follows:
  1. (A) → (B) : [Home] is inputted to the system (Reason: [Control]+[a] (generated by (A)) is inputted by x11keymacs, which can be successfully translated)
  2. (B) → (A) : [Control]+[a] is inputted to the system (Reason: x11keymacs translates first, but it cannot understand [CapsLock]+[a])
  In this case, the first one shall be the desired behavior. However, I have seen that in some systems other than OpenSUSE 11.4, the second behavior is observed. In such cases, however, you can cope with it by modifying the code as follows (not a elegant solution, though):

  diff --git a/emacs.cpp b/emacs.cpp
  index 7e17802..d32bdca 100644
  --- a/emacs.cpp
  +++ b/emacs.cpp
  @@ -73,7 +73,7 @@ void EmacsConverter::typeKey(__u16 code, int metaKeys)
           BIT_LEFTALT, BIT_RIGHTALT,
       };
       static const __u16 keys[] = {
  -        KEY_LEFTCTRL, KEY_RIGHTCTRL, 
  +        KEY_CAPSLOCK, KEY_RIGHTCTRL, 
           KEY_LEFTSHIFT, KEY_RIGHTSHIFT, 
           KEY_LEFTALT, KEY_RIGHTALT,
       };
  @@ -139,7 +139,7 @@ void EmacsConverter::typeKey(__u16 code, int metaKeys)
   bool EmacsConverter::handleKeyInput(struct input_event* input)
   {
       switch (input->code) {
  -    case KEY_LEFTCTRL:
  +    case KEY_CAPSLOCK:
           return handleMetaKeyInput(input, BIT_LEFTCTRL);
       case KEY_RIGHTCTRL:
           return handleMetaKeyInput(input, BIT_RIGHTCTRL);

Technical Information

(TO BE TRANSLATED)

Related Information and Acknowledgement

Linux Input Subsystemの使い方

This page describes the usage of Linux Input Subsystem from applications. I would like to acknowledge that the tool provided here is implemented using the information provided on this site.

WindowsでEmacsキーバインド

AutoHotKey script (emacs.ahk) for realizing Emacs keybindings on Win32 is distributed. I personally uses this script when I need to use Windows, and the idea of emacs.cpp is inspired from this script.

xfumble

A more generalized keybinding configuration tool with customizable features. It includes Emacs-keybinding configuration file as a default, and I personally recommend using it instead of x11keymacs. It uses X11 functionalities for keyboard input handling, and seem to differ from the x11keymacs in many ways with respect to the implementation techniques.

窓使いの憂鬱 for Linux & Mac (Darwin)

Linux/Mac-version of "窓使いの憂鬱" is distributed on this site. I found from the souce code that it uses similar techniques for keyboard input processing as done by mine, using the Linux input subsystem. I found this after I finished implemented x11keymacs, and regret I should have added window title/class features on it instead of reinventing the wheel.

History

• 2011-08-06: Modified to ignore empty lines in regexp pattern file
• 2011-07-07: First version released.

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Last modified: Fri Nov 25 06:55:45 2011