A fork of ruby-debug(19) that works on 1.9.2 and 1.9.3 and installs easily for rvm/rbenv rubies. ruby >= 2.0 are not supported - see below.

Build Status


$ gem install debugger

# If install fails, try passing headers path
$ gem install debugger -- --with-ruby-include=PATH_TO_HEADERS

For Windows install instructions, see OLD_README.

Supported Rubies

On install, debugger tries to find your ruby's headers. If it's unable to find them and your ruby is a patch release, it will use headers included with debugger-ruby_core_source. For the list of 1.9.X rubies supported by debugger see here. If your ruby is not an official patch release i.e. head, dev or an rc, you are responsible for having headers and setting them with --with-ruby-include.


Wherever you need a debugger, simply:

require 'debugger'; debugger

To use with bundler, drop in your Gemfile:

gem 'debugger'


At initialization time, debugger loads config files, executing their lines as if they were actual commands a user has typed. config files are loaded from two locations:

  • ~/.rdebugrc (~/rdebug.ini for windows)
  • $PWD/.rdebugrc ($PWD/rdebug.ini for windows)

To see debugger's current settings, use the set command.

Using Commands

For a list of commands:

(rdb: 1) help

Most commands are described in rdebug's man page

$ gem install gem-man
$ man rdebug

Remote Debugging

To debug a separate process remotely (such as unicorn) try:

  Debugger.wait_connection = true

Then you can do

 $ rdebug -c

More documentation

Some thorough documentation of debugger is found with this bashdb tutorial. For emacs and debugger usage, see another bashdb tutorial

Reason for Fork

  • ruby-debug19 maintainer isn't maintaining:
    • Despite patches from ruby core, no gem release in 2+ years! - 9/1/09.
    • Requests to release a known working 1.9.3 version have been ignored.
    • Doesn't respond to rubyforge issues and doesn't have github issues open.
  • Current install is painful. Requires either manually downloading gems from rubyforge and installing with compiler flags or recompiling ruby.
  • We need a decent ruby debugger for future rubies!

What's different from ruby-debug19

  • Major
    • Works on 1.9.2 and 1.9.3
    • 1.9.2 points to ruby-debug-base19-0.11.25 headers
    • 1.9.3 points to ruby-debug-base19-0.11.26 headers
    • Install painlessly for rvm and rbenv rubies i.e. no compiler flags needed
    • No downloading ruby source during install - was behavior of old ruby_core_source dependency
    • Add output adapters, Printers, to support output besides plain text e.g. xml
    • A new and improved test suite
    • Passing tests are up on travis-ci
    • Fix several bugs
    • Fix LocalJumpError caused by using proc in extconf.rb
    • Fix where command failing at top level
    • See changelog for more
  • Minor
    • The gem name matches the module namespace, Debugger, and main required file, debugger.
    • autolist and autoeval enabled by default
    • ruby-debug-base19 and ruby-debug19 are released as one gem
    • Rake tasks have been updated
    • No more $LOAD_PATH manipulation or runtime code outside of lib
    • man page available via gem-man
    • Test helpers for third-party debugger libraries can be accessed from debugger/test. See debugger-xml for an example


Please report them on github.

Known Issues

  • Only 1.9.2 and 1.9.3 are supported. For 2.X rubies, consider using byebug or debugger2.
  • If you place a debugger call at the end of a block, debugging will start at the next step and outside of your block. A simple work-around is to place a meaningless step (i.e. puts "STAY") at the end of your block and before debugger.


See here for contribution policies. Let's keep this working for the ruby community!


Licensing due to the complicated forking history of this project. Licensing is BSD throughout most of the repository except for portions of emacs/, doc/ and old_scripts/ which are GPL.


  • Thanks to the original authors: Kent Sibilev and Mark Moseley
  • Thanks to astashov for bringing in a new and improved test suite, adding printers support and various bug fixes.
  • Thanks to windwiny for starting the port to 2.0.0
  • Contributors: ericpromislow, jnimety, adammck, hipe, FooBarWidget, aghull, deivid-rodriguez, tessi, os97673, arthurnn
  • Fork started on awesome @relevance fridays!


  • Port some of bashdb's docs
  • Use ~/.debuggerrc and bin/debugger and gracefully deprecate rdebug*
  • Work with others willing to tackle jruby, rubinius or windows support