Byebug

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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 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.

Build Status

Linux & OSX Tra

Windows Vey

Requirements

  • Required: MRI 2.0.0 or higher. For debugging ruby 1.9.3 or older, use debugger.

  • Recommended:

    • MRI 2.1.7 or higher.
    • MRI 2.2.3 or higher.

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.

Byebug's commands

Command Aliases Subcommands
backtrace bt where
break
catch
condition
continue
delete
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.

Contribute

See Getting Started with Development.

Credits

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

  • @ko1, author of the awesome TracePoint API for Ruby.
  • @cldwalker, debugger's maintainer.
  • @denofevil, author of debase, the starting point of this.
  • @kevjames3 for testing, bug reports and the interest in the project.
  • @FooBarWidget for working and helping with remote debugging.