# Byebug [![Version][VersionBadge]][VersionURL] [![Build][TravisBadge]][TravisURL] [![Climate][CodeClimateBadge]][CodeClimateURL] [![Dependencies][GemnasiumBadge]][GemnasiumURL] [![Coverage][CoverallsBadge]][CoverallsURL] [![Gittip][GittipBadge]][GittipURL] _Debugging in Ruby 2_ 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 can do four main kinds of things to help you catch bugs in the act: * Start your program or attach to it, specifying anything that might affect its behavior. * Make your program stop on specified conditions. * Examine what has happened when your program has stopped. * Change things in your program, so you can experiment with correcting the effects of one bug and go on to learn about another. ## Install $ gem install byebug ## Usage Simply drop byebug wherever you want to start debugging and the execution will stop there. If you are debugging rails, start the server and once the execution gets to your `byebug` command you will get a debugging prompt. Former [debugger](https://github.com/cldwalker/debugger) or [ruby-debug](https://github.com/mark-moseley/ruby-debug) users, notice: * Some gems (rails, rspec) implement debugging flags (-d, --debugger) that early require and start the debugger. These flags are a performance penalty and Byebug doesn't need them anymore so my recommendation is not to use them. * The startup configuration file is now called `.byebugrc` instead of `.rdebugrc`. ## What's different from debugger * Works on Ruby 2.x and it doesn't on 1.9.x. * Has no MRI internal source code dependencies, just a clean API. * Fixes all of debugger's open bugs in its issue tracker and provides some enhancements, such as a markdown guide or the fact that `byebug` can now be placed at the end of a block or method call. * Actively mantained. * Editor agnostic: no external editor built-in support. * Pry command is built-in. No need of external gem like debugger-pry. ## Semantic Versioning Byebug tries to follow [semantic versioning](http://semver.org). Backwards compatibility doesn't seem like a critic issue for a debugger because it's not supposed to be used permanently by any program, let alone in production environments. However, I still like the idea of giving some meaning to version changes. Byebug's public API is determined by its set of commands Command | Aliases | Subcommands ----------- |:------------ |:----------- `backtrace` | `bt` `where` | `break` | | `catch` | | `condition` | | `continue` | | `delete` | | `disable` | | `breakpoints` `display` `display` | | `down` | | `edit` | | `enable` | | `breakpoints` `display` `finish` | | `frame` | | `help` | | `info` | | `args` `breakpoints` `catch` `display` `file` `files` `global_variables` `instance_variables` `line` `locals` `program` `stack` `variables` `irb` | | `kill` | | `list` | | `method` | | `instance` `iv` `next` | | `p` | `eval` | `pp` | | `pry` | | `ps` | | `putl` | | `quit` | `exit` | `reload` | | `restart` | | `save` | | `set` | | `args` `autoeval` `autoirb` `autolist` `autoreload` `basename` `callstyle` `callstyle` `forcestep` `fullpath` `history` `linetrace` `linetrace_plus` `listsize` `post_mortem` `stack_on_error` `testing` `verbose` `width` `show` | | `args` `autoeval` `autoirb` `autolist` `autoreload` `basename` `callstyle` `callstyle` `commands` `forcestep` `fullpath` `history` `linetrace` `linetrace_plus` `listsize` `post_mortem` `stack_on_error` `verbose` `width` `skip` | | `source` | | `step` | | `thread` | | `current` `list` `resume` `stop` `switch` `trace` | | `undisplay` | | `up` | | `var` | | `class` `constant` `global` `instance` `local` `ct` ## Getting Started Read [byebug's markdown guide](https://github.com/deivid-rodriguez/byebug/blob/master/GUIDE.md) to get started. Proper documentation will be eventually written. ## Related projects * [pry-byebug](https://github.com/deivid-rodriguez/pry-byebug) adds `next`, `step`, `finish`, `continue` and `break` commands to pry using byebug. * [ruby-debug-passenger](https://github.com/davejamesmiller/ruby-debug-passenger) adds a rake task that restarts Passenger with byebug connected. * [minitest-byebug](https://github.com/kaspth/minitest-byebug) starts a byebug session on minitest failures. * [sublime-debugger](https://github.com/shuky19/sublime_debugger) provides a plugin for ruby debugging on Sublime Text. ## Future (possible) directions * JRuby support. * Libify and test byebug's executable. * Add printers support. ## Credits Everybody who has ever contributed to this forked and reforked piece of software, specially: * Kent Sibilev and Mark Moseley, original authors of [ruby-debug](https://github.com/mark-moseley/ruby-debug). * Gabriel Horner, [debugger](https://github.com/cldwalker/debugger)'s mantainer. * Koichi Sasada, author of the new C debugging API for Ruby. * Dennis Ushakov, author of [debase](https://github.com/denofevil/debase), the starting point of this. * @kevjames3 for testing, bug reports and the interest in the project. 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