rbenv lets you easily switch between multiple versions of Ruby. It's simple, unobtrusive, understandable, and follows in the Unix tradition of single-purpose tools that do one thing well.
* **Need to be loaded into your shell.** Instead, rbenv's shim approach works by adding a directory to your `$PATH`.
* **Override shell commands like `cd`.** That's just obnoxious!
* **Have a configuration file.** There's nothing to configure except which version of Ruby you want to use.
* **Install Ruby.** You can build and install Ruby yourself, or use [ruby-build](https://github.com/sstephenson/ruby-build.git) to automate the process.
* **Manage gemsets.** [Bundler](http://gembundler.com/) is a better way to manage application dependencies. If you have projects that are not yet using Bundler you can install the [rbenv-gemset](https://github.com/jamis/rbenv-gemset) plugin.
* **Require changes to Ruby libraries for compatibility.** The simplicity of rbenv means as long as it's in your `$PATH`, [nothing](https://rvm.beginrescueend.com/integration/bundler/) [else](https://rvm.beginrescueend.com/integration/capistrano/) needs to know about it.
* **Prompt you with warnings when you switch to a project.** Instead of executing arbitrary code, rbenv reads just the version name from each project. There's nothing to "trust."
## How It Works
rbenv operates on the per-user directory `~/.rbenv`. Version names in rbenv correspond to subdirectories of `~/.rbenv/versions`. For example, you might have `~/.rbenv/versions/1.8.7-p354` and `~/.rbenv/versions/1.9.3-preview1`.
Each version is a working tree with its own binaries, like `~/.rbenv/versions/1.8.7-p354/bin/ruby` and `~/.rbenv/versions/1.9.3-preview1/irb`. rbenv makes _shim binaries_ for every such binary across all installed versions of Ruby.
These shims are simple wrapper scripts that live in `~/.rbenv/shims` and detect which Ruby version you want to use. They insert the directory for the selected version at the beginning of your `$PATH` and then execute the corresponding binary.
Because of the simplicity of the shim approach, all you need to use rbenv is `~/.rbenv/shims` in your `$PATH`.
## Installation
rbenv is a young project, so for now you must install it from source.
3. Add rbenv's shims directory to your `$PATH` and set up Bash autocompletion. (If you prefer not to load rbenv in your shell, you can manually add `$HOME/.rbenv/shims` to your path in step 2.)
$ echo 'eval "$(rbenv init -)"' >> .bash_profile
4. Restart your shell. You can now begin using rbenv.
$ exec $SHELL
5. Install Ruby versions into `~/.rbenv/versions`. For example, to install Ruby 1.9.2-p290, download and unpack the source, then run:
6. Rebuild the shim binaries. You should do this any time you install a new Ruby binary (for example, when installing a new Ruby version, or when installing a gem that provides a binary).
$ rbenv rehash
## Usage
Like `git`, the `rbenv` command delegates to subcommands based on its first argument. The most common subcommands are:
* **set-default** — sets the default version of Ruby to be used in all shells by writing the version name to the `~/.rbenv/default` file. This version can be overridden by a per-project `.rbenv-version` file, or by setting the `RBENV_VERSION` environment variable.
$ rbenv set-default 1.9.2-p290
The special version name `system` tells rbenv to use the system Ruby (detected by searching your `$PATH`).
* **set-local** — sets a local per-project Ruby version by writing the version name to an `.rbenv-version` file in the current directory. This version overrides the default, and can be overridden itself by setting the `RBENV_VERSION` environment variable.
$ rbenv set-local rbx-1.2.4
* **versions** — 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-preview1 (set by /Users/sam/.rbenv/default)
jruby-1.6.3
rbx-1.2.4
ree-1.8.7-2011.03
* **version** — displays the currently active Ruby version, along with information on how it was set.
$ rbenv version
1.8.7-p352 (set by /Volumes/37signals/basecamp/.rbenv-version)
## Contributing
The rbenv source code is [hosted on GitHub](https://github.com/sstephenson/rbenv). It's clean, modular, and easy to understand, even if you're not a shell hacker.
Please feel free to submit pull requests and file bugs on the [issue tracker](https://github.com/sstephenson/rbenv/issues).
## License
(The MIT license)
Copyright (c) 2011 Sam Stephenson
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
