Groom your app’s Ruby environment with rbenv.
Use rbenv to pick a Ruby version for your application and guarantee that your development environment matches production. Put rbenv to work with Bundler for painless Ruby upgrades and bulletproof deployments.
Powerful in development. Specify your app’s Ruby version once, in a single file. Keep all your teammates on the same page. No headaches running apps on different versions of Ruby. Just Works™ from the command line and with app servers like Pow. Override the Ruby version anytime: just set an environment variable.
Rock-solid in production. Your application’s executables are its
interface with ops. With rbenv and Bundler
you’ll never again need to
cd in a cron job or Chef recipe to
ensure you’ve selected the right runtime. The Ruby version
dependency lives in one place—your app—so upgrades and rollbacks are
atomic, even when you switch versions.
One thing well. rbenv is concerned solely with switching Ruby versions. It’s simple and predictable. A rich plugin ecosystem lets you tailor it to suit your needs. Compile your own Ruby versions, or use the ruby-build plugin to automate the process. Specify per-application environment variables with rbenv-vars. See more plugins on the wiki.
Table of Contents
- How It Works
- Command Reference
- Environment variables
How It Works
At a high level, rbenv intercepts Ruby commands using shim
executables injected into your
PATH, determines which Ruby version
has been specified by your application, and passes your commands along
to the correct Ruby installation.
When you run a command like
rake, your operating system
searches through a list of directories to find an executable file with
that name. This list of directories lives in an environment variable
PATH, with each directory in the list separated by a colon:
PATH are searched from left to right, so a matching
executable in a directory at the beginning of the list takes
precedence over another one at the end. In this example, the
/usr/local/bin directory will be searched first, then
rbenv works by inserting a directory of shims at the front of your
Through a process called rehashing, rbenv maintains shims in that
directory to match every Ruby command across every installed version
ruby, and so on.
Shims are lightweight executables that simply pass your command along
to rbenv. So with rbenv installed, when you run, say,
operating system will do the following:
- Search your
PATHfor an executable file named
- Find the rbenv shim named
rakeat the beginning of your
- Run the shim named
rake, which in turn passes the command along to rbenv
Choosing the Ruby Version
When you execute a shim, rbenv determines which Ruby version to use by reading it from the following sources, in this order:
RBENV_VERSIONenvironment variable, if specified. You can use the
rbenv shellcommand to set this environment variable in your current shell session.
.ruby-versionfile found by searching the directory of the script you are executing and each of its parent directories until reaching the root of your filesystem.
.ruby-versionfile found by searching the current working directory and each of its parent directories until reaching the root of your filesystem. You can modify the
.ruby-versionfile in the current working directory with the
~/.rbenv/versionfile. You can modify this file using the
rbenv globalcommand. If the global version file is not present, rbenv assumes you want to use the “system” Ruby—i.e. whatever version would be run if rbenv weren’t in your path.
Locating the Ruby Installation
Once rbenv has determined which version of Ruby your application has specified, it passes the command along to the corresponding Ruby installation.
Each Ruby version is installed into its own directory under
~/.rbenv/versions. For example, you might have these versions
Version names to rbenv are simply the names of the directories in
Compatibility note: rbenv is incompatible with RVM. Please make sure to fully uninstall RVM and remove any references to it from your shell initialization files before installing rbenv.
If you’re on Mac OS X, consider installing with Homebrew.
Basic GitHub Checkout
This will get you going with the latest version of rbenv and make it easy to fork and contribute any changes back upstream.
Check out rbenv into
$ git clone https://github.com/rbenv/rbenv.git ~/.rbenv
Optionally, try to compile dynamic bash extension to speed up rbenv. Don’t worry if it fails; rbenv will still work normally:
$ cd ~/.rbenv && src/configure && make -C src
$PATHfor access to the
$ echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.bash_profile
Ubuntu Desktop note: Modify your
Zsh note: Modify your
~/.zshrcfile instead of
~/.rbenv/bin/rbenv initfor shell-specific instructions on how to initialize rbenv to enable shims and autocompletion.
Restart your shell so that PATH changes take effect. (Opening a new terminal tab will usually do it.) Now check if rbenv was set up:
$ type rbenv #=> "rbenv is a function"
If you’ve installed rbenv manually using git, you can upgrade your installation to the cutting-edge version at any time.
$ cd ~/.rbenv $ git pull
To use a specific release of rbenv, check out the corresponding tag:
$ cd ~/.rbenv $ git fetch $ git checkout v0.3.0
If you’ve installed via Homebrew, then upgrade
$ brew update $ brew upgrade rbenv ruby-build
Homebrew on Mac OS X
$ brew update $ brew install rbenv $ rbenv init
You’ll only ever have to run
rbenv init once.
How rbenv hooks into your shell
Skip this section unless you must know what every line in your shell profile is doing.
rbenv init is the only command that crosses the line of loading
extra commands into your shell. Coming from RVM, some of you might be
opposed to this idea. Here’s what
rbenv init actually does:
Sets up your shims path. This is the only requirement for rbenv to function properly. You can do this by hand by prepending
Installs autocompletion. This is entirely optional but pretty useful. Sourcing
~/.rbenv/completions/rbenv.bashwill set that up. There is also a
~/.rbenv/completions/rbenv.zshfor Zsh users.
Rehashes shims. From time to time you’ll need to rebuild your shim files. Doing this automatically makes sure everything is up to date. You can always run
Installs the sh dispatcher. This bit is also optional, but allows rbenv and plugins to change variables in your current shell, making commands like
rbenv shellpossible. The sh dispatcher doesn’t do anything crazy like override
cdor hack your shell prompt, but if for some reason you need
rbenvto be a real script rather than a shell function, you can safely skip it.
rbenv init - for yourself to see exactly what happens under the
Installing Ruby versions
rbenv install command doesn’t ship with rbenv out of the box, but
is provided by the ruby-build project. If you installed it either
as part of GitHub checkout process outlined above or via Homebrew, you
should be able to:
# list all available versions: $ rbenv install -l # install a Ruby version: $ rbenv install 2.0.0-p247
Alternatively to the
install command, you can download and compile
Ruby manually as a subdirectory of
~/.rbenv/versions/. An entry in
that directory can also be a symlink to a Ruby version installed
elsewhere on the filesystem. rbenv doesn’t care; it will simply treat
any entry in the
versions/ directory as a separate Ruby version.
Installing Ruby gems
Once you’ve installed some Ruby versions, you’ll want to install gems.
First, ensure that the target version for your project is the one you want by
rbenv version (see Command Reference). Select
another version using
rbenv local 2.0.0-p247, for example. Then, proceed to
install gems as you normally would:
$ gem install bundler
You don’t need sudo to install gems. Typically, the Ruby versions will be installed and writeable by your user. No extra privileges are required to install gems.
Check the location where gems are being installed with
$ gem env home # => ~/.rbenv/versions/<ruby-version>/lib/ruby/gems/...
Uninstalling Ruby versions
As time goes on, Ruby versions you install will accumulate in your
To remove old Ruby versions, simply
rm -rf the directory of the
version you want to remove. You can find the directory of a particular
Ruby version with the
rbenv prefix command, e.g.
The ruby-build plugin provides an
rbenv uninstall command to
automate the removal process.
The simplicity of rbenv makes it easy to temporarily disable it, or uninstall from the system.
- To disable rbenv managing your Ruby versions, simply remove the
rbenv initline from your shell startup configuration. This will remove rbenv shims directory from PATH, and future invocations like
rubywill execute the system Ruby version, as before rbenv.
rbenv will still be accessible on the command line, but your Ruby
apps won’t be affected by version switching.
To completely uninstall rbenv, perform step (1) and then remove its root directory. This will delete all Ruby versions that were installed under
rm -rf `rbenv root`
If you’ve installed rbenv using a package manager, as a final step perform the rbenv package removal. For instance, for Homebrew:
brew uninstall rbenv
rbenv command delegates to subcommands based on its
first argument. The most common subcommands are:
Sets a local application-specific Ruby version by writing the version
name to a
.ruby-version file in the current directory. This version
overrides the global version, and can be overridden itself by setting
RBENV_VERSION environment variable or with the
$ rbenv local 1.9.3-p327
When run without a version number,
rbenv local reports the currently
configured local version. You can also unset the local version:
$ rbenv local --unset
Sets the global version of Ruby to be used in all shells by writing
the version name to the
~/.rbenv/version file. This version can be
overridden by an application-specific
.ruby-version file, or by
RBENV_VERSION environment variable.
$ rbenv global 1.8.7-p352
The special version name
system tells rbenv to use the system Ruby
(detected by searching your
When run without a version number,
rbenv global reports the
currently configured global version.
Sets a shell-specific Ruby version by setting the
environment variable in your shell. This version overrides
application-specific versions and the global version.
$ rbenv shell jruby-1.7.1
When run without a version number,
rbenv shell reports the current
RBENV_VERSION. You can also unset the shell version:
$ rbenv shell --unset
Note that you’ll need rbenv’s shell integration enabled (step 3 of
the installation instructions) in order to use this command. If you
prefer not to use shell integration, you may simply set the
RBENV_VERSION variable yourself:
$ export RBENV_VERSION=jruby-1.7.1
Lists all Ruby versions known to rbenv, and shows an asterisk next to the currently active version.
$ rbenv versions 1.8.7-p352 1.9.2-p290 * 1.9.3-p327 (set by /Users/sam/.rbenv/version) jruby-1.7.1 rbx-1.2.4 ree-1.8.7-2011.03
Displays the currently active Ruby version, along with information on how it was set.
$ rbenv version 1.9.3-p327 (set by /Users/sam/.rbenv/version)
Installs shims for all Ruby executables known to rbenv (i.e.,
~/.rbenv/versions/*/bin/*). Run this command after you install a new
version of Ruby, or install a gem that provides commands.
$ rbenv rehash
Displays the full path to the executable that rbenv will invoke when you run the given command.
$ rbenv which irb /Users/sam/.rbenv/versions/1.9.3-p327/bin/irb
Lists all Ruby versions with the given command installed.
$ rbenv whence rackup 1.9.3-p327 jruby-1.7.1 ree-1.8.7-2011.03
You can affect how rbenv operates with the following settings:
||Specifies the Ruby version to be used.
||Defines the directory under which Ruby versions and shims reside.
||Outputs debug information.
||see wiki||Colon-separated list of paths searched for rbenv hooks.|
||Directory to start searching for
The rbenv source code is hosted on GitHub. It’s clean, modular, and easy to understand, even if you’re not a shell hacker.
Tests are executed using Bats:
$ bats test $ bats test/<file>.bats
Please feel free to submit pull requests and file bugs on the issue tracker.