Byebug

Byebug is a simple to use, feature rich debugger for Ruby. It uses the TracePoint API for execution control and the Debug Inspector API for call stack navigation, so it doesn't depend on internal core sources. It's developed as a C extension, so it's fast. And it has a full test suite so it's reliable.

It allows you to see what is going on inside a Ruby program while it executes and offers many of the traditional debugging features such as:

Build Status

Linux

Windows

Requirements

Install

gem install byebug

Usage

From within the Ruby code

Simply drop

byebug

wherever you want to start debugging and the execution will stop there. If you were debugging Rails, for example, you would add byebug to your code.

def index
  byebug
  @articles = Article.find_recent
end

And then start a Rails server.

bin/rails s

Once the execution gets to your byebug command you will get a debugging prompt.

From the command line

If you want to debug a Ruby script without editing it, you can invoke byebug from the command line.

byebug myscript.rb

Byebug's commands

Command     | Aliases      | Subcommands
----------- |:------------ |:-----------
`backtrace` | `bt` `where` |
`break`     |              |
`catch`     |              |
`condition` |              |
`continue`  |              |
`delete`    |              |
`debug`     |              |
`disable`   |              | `breakpoints` `display`
`display`   |              |
`down`      |              |
`edit`      |              |
`enable`    |              | `breakpoints` `display`
`finish`    |              |
`frame`     |              |
`help`      |              |
`history`   |              |
`info`      |              | `args` `breakpoints` `catch` `display` `file` `line` `program`
`irb`       |              |
`kill`      |              |
`list`      |              |
`method`    |              | `instance`
`next`      |              |
`pry`       |              |
`quit`      |              |
`restart`   |              |
`save`      |              |
`set`       |              | `autoirb` `autolist` `autopry` `autosave` `basename` `callstyle` `fullpath` `histfile` `histsize` `linetrace` `listsize` `post_mortem` `savefile` `stack_on_error` `width`
`show`      |              | `autoirb` `autolist` `autopry` `autosave` `basename` `callstyle` `fullpath` `histfile` `histsize` `linetrace` `listsize` `post_mortem` `savefile` `stack_on_error` `width`
`source`    |              |
`step`      |              |
`thread`    |              | `current` `list` `resume` `stop` `switch`
`tracevar`  |              |
`undisplay` |              |
`up`        |              |
`var`       |              | `all` `constant` `global` `instance` `local`

Semantic Versioning

Byebug tries to follow semantic versioning and tries to bump major version only when backwards incompatible changes are released. Backwards compatibility is targeted to pry-byebug and any other plugins relying on byebug.

Getting Started

Read byebug’s markdown guide to get started. Proper documentation will be eventually written.

Related projects

Contribute

See Getting Started with Development.

Credits

Everybody who has ever contributed to this forked and reforked piece of software, especially: