An extensible, modular GNU Emacs front-end for interacting with external debuggers, brought to you by Rocky Bernstein (@rocky) and Clément Pit-Claudel (@cpitclaudel).

You can install RealGUD from MELPA, a repository of Emacs packages. If you don't have MELPA set up, add the following to your .emacs and restart Emacs:

(require 'package)
(add-to-list 'package-archives '("melpa" . "http://melpa.org/packages/") t)
(package-initialize)

You can then run the following commands to install RealGUD:

M-x package-refresh-contents RET      (to refresh your package database)
M-x package-install RET realgud RET   (to install and compile `realgud` and its dependencies)

Alternatively, you can install RealGUD using el-get or from source directly. See this article in our wiki for more info.

Use M-x load-library RET realgud RET to load RealGUD.

Open a source file, then use M-x realgud:<debugger-name> to start your favorite debugger (for example, you can use M-x realgud:pdb to launch PDB, a Python debugger). RealGUD opens two windows: the command window (showing the debugger's REPL), and the source window, showing your code (with some debuggers, such as realgud:gdb, this window does not appear until you type start in the command window). An solid arrow ▶ indicates the current line in the source window. Grayed out arrows indicate previous positions.

All usual debugger commands work in the command window: for example, you can type n RET in the command window to step forward one source line. But RealGUD's power lies in the source window: in it, most single keys correspond to a debugger action. For example, you can press n in the source window to step forward.

Here is a quick rundown of the most useful commands. “🐁” indicates mouse commands (commands that can be run by clicking on a variable or in the margins). Many of the commands are accessible from the tool bar (tool-bar-mode) and the menu (menu-bar-mode).

• Motion commands

  Command	Action
  n, F10	Next (aka “step over”, “step through”)
  s, SPC, F11	Step (aka “step into”)
  f, S-F11	Finish (aka “step out”, “return”)
  c, F5	Continue (run to next break point)

• Using breakpoints

  Command	Action
  b, F9	Set breakpoint 🐁
  D	Clear breakpoint 🐁 (by number)

• Inspecting variables

  Command	Action
  mouse-2 (middle button)	Inspect variable under cursor (in tooltip) 🐁
  e	Evaluate expression

• Control commands

  Command	Action
  q, S-F5	Quit
  R, r	Run (aka “restart”)
  S	Go to command window

RealGUD supports many external debuggers. Help us support even more!

“⚙” indicates a work-in-progress (contributions welcome!)

Use M-x realgud-track-mode inside an existing shell, or eshell buffer to track an already-running debugger process.

Browse the wiki for more information about setting up, using realgud, exploring features, and lots more.