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inf-ruby provides a REPL buffer connected to a Ruby subprocess.


Via package.el

package.el is the built-in package manager in Emacs 24+. On Emacs 23 you will need to get package.el yourself if you wish to use it.

inf-ruby is available on both major package.el community maintained repos: Marmalade and MELPA.

If you're not already using one of them, follow their installation instructions: Marmalade, MELPA.

And then you can install inf-ruby with the following command:

M-x package-install [RET] inf-ruby [RET]

or by adding this bit of Emacs Lisp code to your Emacs initialization file (.emacs or init.el):

(unless (package-installed-p 'inf-ruby)
  (package-install 'inf-ruby))

If the installation doesn't work try refreshing the package list:

M-x package-refresh-contents [RET]

Via el-get

el-get is another popular package manager for Emacs. If you're an el-get user just do M-x el-get-install.


If you're installing manually, you'll need to:

  • drop the inf-ruby.el file somewhere on your load path (perhaps ~/.emacs.d/vendor)
  • Add the following lines to your .emacs (or init.el) file:
(autoload 'inf-ruby-minor-mode "inf-ruby" "Run an inferior Ruby process" t)
(add-hook 'ruby-mode-hook 'inf-ruby-minor-mode)

Or, for enh-ruby-mode:

(add-hook 'enh-ruby-mode-hook 'inf-ruby-minor-mode)

Installation via package.el interface does the above for you automatically.

Additionally, consider adding

(add-hook 'compilation-filter-hook 'inf-ruby-auto-enter)

to your init file to automatically switch from common Ruby compilation modes to interact with a debugger.

Custom Prompts

If you wish to add other interpreter prompt patterns, see the description in the wiki.

Emacs Prelude

inf-ruby comes bundled in Emacs Prelude. If you're a Prelude user you can start using it right away.



A simple IRB process can be fired up with M-x inf-ruby.


To launch a REPL with project-specific console instead, type M-x inf-ruby-console-auto. It recognizes several project types, including Rails, gems and anything with racksh in their Gemfile.


When entered, this mode runs comint-mode-hook and inf-ruby-mode-hook (in that order).


  • ruby-switch-to-inf switches the current buffer to the ruby process buffer.
  • ruby-send-definition sends the current definition to the ruby process.
  • ruby-send-region sends the current region to the ruby process.
  • ruby-send-definition-and-go and ruby-send-region-and-go switch to the ruby process buffer after sending their text.


  • RET after the end of the process' output sends the text from the end of process to point.
  • RET before the end of the process' output copies the sexp ending at point to the end of the process' output, and sends it.
  • DEL converts tabs to spaces as it moves back.
  • TAB completes the input at point. IRB, Pry and Bond completion is supported.
  • C-M-q does TAB on each line starting within following expression.
  • Paragraphs are separated only by blank lines. # start comments.
  • If you accidentally suspend your process, use comint-continue-subjob to continue it.


To see the list of the keybindings defined by inf-ruby-minor-mode, type M-x describe-function [RET] inf-ruby-minor-mode [RET].


  • The REPL buffer doesn't seem to react to input?

    Try putting IRB.conf[:USE_READLINE] = false into your ~/.irbrc (issue #51).

  • Pry raises ZeroDivisionError in lib/pry/pager.rb?

    Put Pry.config.pager = false if ENV["INSIDE_EMACS"] into your ~/.pryrc.

  • Pry prints �[0G right after start?

    Put Pry.config.correct_indent = false if ENV["INSIDE_EMACS"] into your ~/.pryrc.

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