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A fork of ruby-debug(19) that works on 1.9.2 and 1.9.3 and installs easily for rvm/rbenv rubies.

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 rubies supported by debugger see here. If your ruby is not a 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'

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
    • Fix LocalJumpError caused by using proc in extconf.rb
    • Fix where command failing at top level
    • Passing tests are up on travis-ci
  • Minor
    • The gem name matches the module namespace, Debugger, and main required file, debugger.
    • 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


Please report them on github.

Known Issues

  • 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!


  • Thanks to the original authors: Kent Sibilev and Mark Moseley
  • Contributors: ericpromislow, jnimety, adammck
  • Fork started on awesome @relevance fridays!


  • Fix test/test-*.rb
  • Work with others willing to tackle jruby, rubinius or windows support