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.
Optionally sets $RUBYOPT is a second argument is given.
Additionally sets $RUBY, $RUBY_ENGINE, $RUBY_VERSION and $GEM_ROOT.
Calls hash -r to clear the command-lookup hash-table.
Fuzzy matching of Rubies by name.
Defaults to the system Ruby.
Supports bash and zsh.
Small (~80 LOC).
Has tests.

Anti-Features

Does not hook cd.
Does not install executable shims.
Does not require Rubies be installed into your home directory.
Does not automatically switch Rubies upon login or when changing directories.
Does not require write-access to the Ruby directory in order to install gems.

Install

wget https://github.com/downloads/postmodern/chruby/chruby-0.2.3.tar.gz
tar -xzvf chruby-0.2.3.tar.gz
cd chruby-0.2.3/
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/downloads/postmodern/chruby/chruby-0.2.3.tar.gz.asc
gpg --verify chruby-0.2.3.tar.gz.asc chruby-0.2.3.tar.gz

Homebrew

chruby can also be installed with homebrew:

brew install https://raw.github.com/postmodern/chruby/master/homebrew/chruby.rb

Rubies

Once chruby has been installed, you will probably want to install additional Rubies. This can be done with the ruby-build utility or manually:

Configuration

Add the following lines to your ~/.bashrc or ~/.profile file:

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

RUBIES=(/usr/local/{ruby,jruby,rubinius}*)

System Wide

Add the following to /etc/profile.d/chruby.sh or /etc/profile:

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

RUBIES=(
  /usr/local/ruby-1.9.3-p327
  /usr/local/jruby-1.7.0
  /usr/local/rubinius-2.0.0-rc1
)

Migrating

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

Default Ruby

If you wish to set a default Ruby, simply call chruby in ~/.bashrc:

chruby 1.9.3

Examples

List available Rubies:

$ chruby
   ruby-1.9.3-p327
   jruby-1.7.0
   rubinius-2.0.0-rc1

Select a Ruby:

$ chruby 1.9.3
$ chruby
 * ruby-1.9.3-p327
   jruby-1.7.0
   rubinius-2.0.0-rc1
$ echo $PATH
/home/hal/.gem/ruby/1.9.3/bin:/usr/local/ruby-1.9.3-p327/lib/ruby/gems/1.9.1/bin:/usr/local/ruby-1.9.3-p327/bin:/usr/lib64/qt-3.3/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/home/hal/bin:/home/hal/bin
$ echo $GEM_HOME
/home/hal/.gem/ruby/1.9.3
$ echo $GEM_PATH
/home/hal/.gem/ruby/1.9.3:/usr/local/ruby-1.9.3-p327/lib/ruby/gems/1.9.1

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

Switch to an arbitrary Ruby on the fly:

$ chruby_use /path/to/ruby

Cron

Select a Ruby within a cron job:

30 18 * * *   bash -lc "chruby 1.9.3 && /path/to/script"

Alternatives

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

Credits

mpapis for reviewing the code.