Towards Simplicity: From rbenv to chruby

chruby is a Ruby version manager: a tool that makes easy to switch Ruby version along with the context either on a local directory or system-wide basis. What makes chruby stand out is its design simplicity. Also, it has only ~90 LoC.

Both rbenv and rvm may seem unnecessarily complicated. The former operates on shims and does context switching each time any Ruby or gem binary is executed. It requires to run rbenv rehash each time there is a new binary installed. The latter overrides cd command for that purpose (hence it is done only once), but it can also install Ruby, manage gemsets and more. Those additions make rvm feel heavy and complex. chruby uses PROMPT_COMMAND to switch the context.

Installing chruby

chruby can be installed in various ways. For OSX, it is as simple as:

brew install chruby

Next, add the two following lines to your shell profile file (.bashrc, .zshrc, etc.)

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

In addition to that, I use Bundler to manage dependencies - which makes gemsets obsolete - and ruby-build to install Ruby versions; I keep them under ~/.rubies:

λ brew install ruby-build
λ ruby-build 1.9.3-p392 ~/.rubies/ruby-1.9.3-p392
λ ruby-build jruby-1.7.3 ~/.rubies/jruby-1.7.3

Using chruby

To see a list of available Ruby versions, type:

λ chruby

To switch between Ruby versions, type:

λ chruby jruby-1.7.3
λ chruby ruby-1.9.3

To use the system Ruby, type:

λ chruby system

To set default Ruby, put the following line inside your shell profile file (e.g. .bashrc, .zshrc, etc):

λ chruby ruby-1.9

To specify local, per-project Ruby version, put its name inside .ruby-version file in that project directory.

Summary

chruby provides the most elegant way to manage Ruby versions. It does only one thing, without unnecessary additions and complications.