chruby

Changes the current Ruby.

Features

• Updates $PATH.
  • Also adds RubyGems bin/ directories to $PATH.
• Correctly sets $GEM_HOME and $GEM_PATH.
  • Users: gems are installed into ~/.gem/$ruby/$version.
  • Root: gems are installed directly into /path/to/$ruby/$gemdir.
• Additionally sets $RUBY_ROOT, $RUBY_ENGINE, $RUBY_VERSION and $GEM_ROOT.
• Optionally sets $RUBYOPT if second argument is given.
• Calls hash -r to clear the command-lookup hash-table.
• Fuzzy matching of Rubies by name.
• Defaults to the system Ruby.
• Optionally supports auto-switching and the .ruby-version file.
• Supports bash and zsh.
• Small (~100 LOC).
• Has tests.

Anti-Features

• Does not hook cd.
• Does not install executable shims or require regenerating them after installing gems.
• Does not require Rubies be installed into your home directory.
• Does not automatically switch Rubies by default.
• Does not require write-access to the Ruby directory in order to install gems.

Requirements

• bash >= 3 or zsh

Install

wget https://github.com/postmodern/chruby/releases/download/v0.3.9/chruby-0.3.9.tar.gz
tar -xzvf chruby-0.3.9.tar.gz
cd chruby-0.3.9/
sudo make install

PGP

All releases are PGP signed for security. Instructions on how to import my PGP key can be found on my blog. To verify that a release was not tampered with:

wget https://github.com/postmodern/chruby/releases/download/v0.3.9/chruby-0.3.9.tar.gz.asc
gpg --verify chruby-0.3.9.tar.gz.asc chruby-0.3.9.tar.gz

setup.sh

chruby also includes a setup.sh script, which installs chruby. Simply run the script as root or via sudo:

sudo ./scripts/setup.sh

Homebrew

chruby can also be installed with homebrew:

brew install chruby

Or the absolute latest chruby can be installed from source:

brew install chruby --HEAD

Arch Linux

chruby is already included in the AUR:

yaourt -S chruby

Fedora Linux

chruby is available as an rpm on Fedora Copr.

FreeBSD

chruby is included in the official FreeBSD ports collection:

cd /usr/ports/devel/chruby/ && make install clean

Rubies

Manually

Chruby provides detailed instructions for installing additional Rubies:

• Ruby
• JRuby
• Rubinius
• MagLev

ruby-install

You can also use ruby-install to install additional Rubies:

Installing to /opt/rubies or ~/.rubies:

ruby-install ruby
ruby-install jruby
ruby-install rubinius
ruby-install maglev

ruby-build

You can also use ruby-build to install additional Rubies:

Installing to /opt/rubies:

ruby-build 1.9.3-p392 /opt/rubies/ruby-1.9.3-p392
ruby-build jruby-1.7.3 /opt/rubies/jruby-1.7.3
ruby-build rbx-2.0.0-rc1 /opt/rubies/rubinius-2.0.0-rc1
ruby-build maglev-1.0.0 /opt/rubies/maglev-1.0.0

Configuration

Add the following to the ~/.bashrc or ~/.zshrc file:

source /usr/local/share/chruby/chruby.sh

macOS

source $HOMEBREW_PREFIX/opt/chruby/share/chruby/chruby.sh # Or run `brew info chruby` to find out installed directory

Note: macOS does not automatically execute ~/.bashrc, instead try adding to /etc/bashrc.

System Wide

If you wish to enable chruby system-wide, add the following to /etc/profile.d/chruby.sh:

if [ -n "$BASH_VERSION" ] || [ -n "$ZSH_VERSION" ]; then
  source /usr/local/share/chruby/chruby.sh
  ...
fi

This will prevent chruby from accidentally being loaded by /bin/sh, which is not always the same as /bin/bash.

Rubies

When chruby is first loaded by the shell, it will auto-detect Rubies installed in /opt/rubies/ and ~/.rubies/. After installing new Rubies, you must restart the shell before chruby can recognize them.

For Rubies installed in non-standard locations, simply append their paths to the RUBIES variable:

source /usr/local/share/chruby/chruby.sh

RUBIES+=(
  /opt/jruby-1.7.0
  "$HOME/src/rubinius"
)

Migrating

If you are migrating from another Ruby manager, set RUBIES accordingly:

RVM

RUBIES+=(~/.rvm/rubies/*)

rbenv

RUBIES+=(~/.rbenv/versions/*)

rbfu

RUBIES+=(~/.rbfu/rubies/*)

Auto-Switching

If you want chruby to auto-switch the current version of Ruby when you cd between your different projects, simply load auto.sh in ~/.bashrc or ~/.zshrc:

source /usr/local/share/chruby/chruby.sh
source /usr/local/share/chruby/auto.sh

Note: macOS does not automatically source ~/.bashrc. Bash users should create the file ~/.bash_profile with following content:

if [[ -f ~/.profile ]]; then
    source ~/.profile
fi

if [[ $- == *i* ]] && [[ -f ~/.bashrc ]]; then
    source ~/.bashrc
fi

so that the terminal loads ~/.bashrc and ~/.profile (the POSIX one). If ~/.bash_profile exists, Bash users should append the above lines to ~/.bash_profile as needed.

chruby will check the current and parent directories for a .ruby-version file. Other Ruby switchers also understand this file: https://gist.github.com/1912050

If you want to automatically run the version of a gem executable specified in your project's Gemfile, try rubygems-bundler.

Default Ruby

Once you have loaded chruby.sh and/or auto.sh in your shell configuration, you can also set a default Ruby. Simply call the chruby function in ~/.bash_profile or ~/.zprofile:

chruby ruby-1.9

If you have enabled auto-switching, simply create a .ruby-version file:

echo "ruby-1.9" > ~/.ruby-version

RubyGems

Gems installed as a non-root user via gem install will be installed into ~/.gem/$ruby/X.Y.Z. By default, RubyGems will use the absolute path to the currently selected ruby for the shebang of any binstubs it generates. In some cases, this path may contain extra version information (e.g. ruby-2.0.0-p451). To mitigate potential problems when removing rubies, you can force RubyGems to generate binstubs with shebangs that will search for ruby in your $PATH by using gem install --env-shebang (or the equivalent short option -E). This parameter can also be added to your gemrc file.

Integration

For instructions on using chruby with other tools, please see the wiki:

• Capistrano
• Chef
• Cron
• Emacs
• Pow
• Puppet
• Sudo
• Vim
• Fish

Examples

List available Rubies:

$ chruby
   ruby-1.9.3-p392
   jruby-1.7.0
   rubinius-2.0.0-rc1

Select a Ruby:

$ chruby 1.9.3
$ chruby
 * ruby-1.9.3-p392
   jruby-1.7.0
   rubinius-2.0.0-rc1
$ echo $PATH
/home/hal/.gem/ruby/1.9.3/bin:/opt/rubies/ruby-1.9.3-p392/lib/ruby/gems/1.9.1/bin:/opt/rubies/ruby-1.9.3-p392/bin:/usr/lib64/qt-3.3/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/home/hal/bin:/home/hal/bin
$ gem env
RubyGems Environment:
  - RUBYGEMS VERSION: 1.8.23
  - RUBY VERSION: 1.9.3 (2013-02-22 patchlevel 392) [x86_64-linux]
  - INSTALLATION DIRECTORY: /home/hal/.gem/ruby/1.9.3
  - RUBY EXECUTABLE: /opt/rubies/ruby-1.9.3-p392/bin/ruby
  - EXECUTABLE DIRECTORY: /home/hal/.gem/ruby/1.9.3/bin
  - RUBYGEMS PLATFORMS:
    - ruby
    - x86_64-linux
  - GEM PATHS:
     - /home/hal/.gem/ruby/1.9.3
     - /opt/rubies/ruby-1.9.3-p392/lib/ruby/gems/1.9.1
  - GEM CONFIGURATION:
     - :update_sources => true
     - :verbose => true
     - :benchmark => false
     - :backtrace => false
     - :bulk_threshold => 1000
     - "gem" => "--no-rdoc"
  - REMOTE SOURCES:
     - http://rubygems.org/

Switch to JRuby in 1.9 mode:

$ chruby jruby --1.9
$ ruby -v
jruby 1.7.0 (1.9.3p203) 2012-10-22 ff1ebbe on OpenJDK 64-Bit Server VM 1.7.0_09-icedtea-mockbuild_2012_10_17_15_53-b00 [linux-amd64]

Switch back to system Ruby:

$ chruby system
$ echo $PATH
/usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/sbin:/home/hal/bin

Run a command under a Ruby with chruby-exec:

$ chruby-exec jruby -- gem update

Switch to an arbitrary Ruby on the fly:

$ chruby_use /path/to/ruby

Uninstall

1. Remove or comment out chruby from your shell configuration.
2. Restart your shell (ex: exec $SHELL).
3. sudo make uninstall

Alternatives

• RVM
• rbenv
• rbfu*
• ry
• ruby-version*

* Deprecated in favor of chruby.

Endorsements

yeah chruby is nice, does the limited thing of switching really good, the only hope it never grows

-- Michal Papis of RVM

I just looooove chruby For the first time I'm in total control of all aspects of my Ruby installation.

-- Marius Mathiesen

Written by Postmodern, it's basically the simplest possible thing that can work.

-- Steve Klabnik

So far, I'm a huge fan. The tool does what it advertises exactly and simply. The small feature-set is also exactly and only the features I need.

-- Patrick Brisbin

I wrote ruby-version; however, chruby is already what ruby-version wanted to be. I've deprecated ruby-version in favor of chruby.

-- Wil Moore III

Credits

• mpapis for reviewing the code.
• havenwood for handling the homebrew formula.
• zendeavor for style fixes.
• #bash, #zsh, #machomebrew for answering all my questions.