Byebug is a simple to use, feature rich debugger for Ruby 2. It uses the new TracePoint API for execution control and the new 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:
- Stepping: Running your program one line at a time.
- Breaking: Pausing the program at some event or specified instruction, to examine the current state.
- Evaluating: Basic REPL functionality, although pry does a better job at that.
- Tracking: Keeping track of the different values of your variables or the different lines executed by your program.
- Required: MRI 2.0.0 or higher. For debugging ruby 1.9.3 or older, use debugger.
- MRI 2.1.8 or higher.
- MRI 2.2.4 or higher.
- MRI 2.3.0 or higher.
- MRI 2.4.0 or higher.
gem install byebug
From within the Ruby code
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.
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.
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`
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
Read byebug’s markdown guide to get started. Proper documentation will be eventually written.
- pry-byebug adds
- ruby-debug-passenger adds a rake task that restarts Passenger with Byebug connected.
- minitest-byebug starts a byebug session on minitest failures.
- sublime_debugger provides a plugin for ruby debugging on Sublime Text.
- atom-byebug provides integration with the Atom editor [EXPERIMENTAL].
Everybody who has ever contributed to this forked and reforked piece of software, especially: