ruby-debug is a fast implementation of the standard debugger debug.rb. The faster execution speed is achieved by utilizing a new hook Ruby C API.


ruby-debug requires Ruby 1.8.4 or higher.

If you are running Linux or Unix you'll need a C compiler so the extension can be compiled when it is installed.


ruby-debug is provided as a RubyGem. To install:

gem install ruby-debug


There are two ways of running ruby-debug.

rdebug executable:

$ rdebug <your-script>

When you start your script this way, the debugger will stop at the first line of code in the script file. So you will be able to set up your breakpoints.

ruby-debug API

The second way is to use the ruby-debug API to interrupt your code execution at runtime.

require 'ruby-debug'
def your_method

When Kernel#debugger method is executed, the debugger is activated and you will be able to inspect and step through your code.


The debug.rb script that comes with the standard library uses Kernel#set_trace_func API. This way it is possible to implement the debugger in pure Ruby, but has a negative effect on the speed of your program execution. For each trace call Ruby interpreter creates a Binding object, even though it is not being used most of the time. ruby-debug library moves most of the functionality of debug.rb to a native extension, this way significantly improving the execution of your program.


See LICENSE for license information.