pyenv/README.md
Sam Stephenson b4a91648eb Hard-wrap
2011-08-11 13:11:37 -05:00

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6.5 KiB
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# Simple Ruby Version Management: rbenv
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.
### rbenv _does…_
* Let you **change the default Ruby version** on a per-user basis.
* Provide support for **per-project Ruby versions**.
* Allow you to **override the Ruby version** with an environment
variable.
### rbenv _does not…_
* **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.
1. Check out rbenv into `~/.rbenv`.
$ cd
$ git clone git://github.com/sstephenson/rbenv.git .rbenv
2. Add `~/.rbenv/bin` to your `$PATH` for access to the `rbenv`
command-line utility.
$ echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> .bash_profile
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
5. Install Ruby versions into `~/.rbenv/versions`. For example, to
install Ruby 1.9.2-p290, download and unpack the source, then run:
$ ./configure --prefix=~/.rbenv/versions/1.9.2-p290
$ make
$ make install
The [ruby-build](https://github.com/sstephenson/ruby-build)
project simplifies this process to a single command:
$ ruby-build 1.9.2-p290 ~/.rbenv/versions/1.9.2-p290
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
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.