Ruby Hacking Guide

This document gives some helpful instructions which should make your experience as a Ruby core developer easier.



It’s common to want to compile things as quickly as possible. Ensuring make has the right --jobs flag will ensure all processors are utilized when building software projects. To do this effectively, you can set MAKEFLAGS in your shell configuration/profile:

# On macOS with Fish shell:
export MAKEFLAGS="--jobs "(sysctl -n hw.ncpu)

# On macOS with Bash/ZSH shell:
export MAKEFLAGS="--jobs $(sysctl -n hw.ncpu)"

# On Linux with Fish shell:
export MAKEFLAGS="--jobs "(nproc)

# On Linux with Bash/ZSH shell:
export MAKEFLAGS="--jobs $(nproc)"

Configure Ruby

It’s generally advisable to use a build directory.

mkdir build
cd build
../configure --prefix $HOME/.rubies/ruby-head
make install

Without Documentation

If you are frequently building Ruby, this will reduce the time it takes to make install.

../configure --disable-install-doc

Running Ruby

Run Local Test Script

You can create a file in the Ruby source root called test.rb. You can build miniruby and execute this script:

make run

If you want more of the standard library, you can use runruby instead of run.

Run Bootstrap Tests

There are a set of tests in bootstraptest/ which cover most basic features of the core Ruby language.

make test

Run Extensive Tests

There are extensive tests in test/ which cover a wide range of features of the Ruby core language.

make test-all

You can run specific tests by specifying their path:

make test-all TESTS=../test/fiber/test_io.rb

Run RubySpec Tests

RubySpec is a project to write a complete, executable specification for the Ruby programming language.

make test-all test-rubyspec