# ruby-build

ruby-build is an [rbenv](https://github.com/rbenv/rbenv) plugin that
provides an `rbenv install` command to compile and install different versions
of Ruby on UNIX-like systems.

You can also use ruby-build without rbenv in environments where you need
precise control over Ruby version installation.

See the [list of releases](https://github.com/rbenv/ruby-build/releases)
for changes in each version.


## Installation

### Installing as an rbenv plugin (recommended)

Installing ruby-build as an rbenv plugin will give you access to the `rbenv
install` command.

    git clone https://github.com/rbenv/ruby-build.git ~/.rbenv/plugins/ruby-build

This will install the latest development version of ruby-build into the
`~/.rbenv/plugins/ruby-build` directory. From that directory, you can check out
a specific release tag. To update ruby-build, run `git pull` to download the
latest changes.

### Installing as a standalone program (advanced)

Installing ruby-build as a standalone program will give you access to the
`ruby-build` command for precise control over Ruby version installation. If you
have rbenv installed, you will also be able to use the `rbenv install` command.

    git clone https://github.com/rbenv/ruby-build.git
    cd ruby-build
    ./install.sh

This will install ruby-build into `/usr/local`. If you do not have write
permission to `/usr/local`, you will need to run `sudo ./install.sh` instead.
You can install to a different prefix by setting the `PREFIX` environment
variable.

To update ruby-build after it has been installed, run `git pull` in your cloned
copy of the repository, then re-run the install script.

### Installing with Homebrew (for OS X users)

Mac OS X users can install ruby-build with the [Homebrew](http://brew.sh)
package manager. This will give you access to the `ruby-build` command. If you
have rbenv installed, you will also be able to use the `rbenv install` command.

*This is the recommended method of installation if you installed rbenv with
Homebrew.*

    brew install ruby-build

Or, if you would like to install the latest development release:

    brew install --HEAD ruby-build

To upgrade the HEAD package use `--fetch-HEAD` option:

    brew upgrade --fetch-HEAD ruby-build

## Usage

Before you begin, you should ensure that your build environment has the proper
system dependencies for compiling the wanted Ruby version (see our [recommendations](https://github.com/rbenv/ruby-build/wiki#suggested-build-environment)).

### Using `rbenv install` with rbenv

To install a Ruby version for use with rbenv, run `rbenv install` with the
exact name of the version you want to install. For example,

    rbenv install 2.2.0

Ruby versions will be installed into a directory of the same name under
`~/.rbenv/versions`.

To see a list of all available Ruby versions, run `rbenv install --list`. You
may also tab-complete available Ruby versions if your rbenv installation is
properly configured.

### Using `ruby-build` standalone

If you have installed ruby-build as a standalone program, you can use the
`ruby-build` command to compile and install Ruby versions into specific
locations.

Run the `ruby-build` command with the exact name of the version you want to
install and the full path where you want to install it. For example,

    ruby-build 2.2.0 ~/local/ruby-2.2.0

To see a list of all available Ruby versions, run `ruby-build --definitions`.

Pass the `-v` or `--verbose` flag to `ruby-build` as the first argument to see
what's happening under the hood.

### Custom definitions

Both `rbenv install` and `ruby-build` accept a path to a custom definition file
in place of a version name. Custom definitions let you develop and install
versions of Ruby that are not yet supported by ruby-build.

See the [ruby-build built-in definitions][definitions] as a starting point for
custom definition files.

[definitions]: https://github.com/rbenv/ruby-build/tree/master/share/ruby-build

### Special environment variables

You can set certain environment variables to control the build process.

* `TMPDIR` sets the location where ruby-build stores temporary files.
* `RUBY_BUILD_BUILD_PATH` sets the location in which sources are downloaded and
  built. By default, this is a subdirectory of `TMPDIR`.
* `RUBY_BUILD_CACHE_PATH`, if set, specifies a directory to use for caching
  downloaded package files.
* `RUBY_BUILD_MIRROR_URL` overrides the default mirror URL root to one of your
  choosing.
* `RUBY_BUILD_SKIP_MIRROR`, if set, forces ruby-build to download packages from
  their original source URLs instead of using a mirror.
* `RUBY_BUILD_ROOT` overrides the default location from where build definitions
  in `share/ruby-build/` are looked up.
* `RUBY_BUILD_DEFINITIONS` can be a list of colon-separated paths that get
  additionally searched when looking up build definitions.
* `CC` sets the path to the C compiler.
* `RUBY_CFLAGS` lets you pass additional options to the default `CFLAGS`. Use
  this to override, for instance, the `-O3` option.
* `CONFIGURE_OPTS` lets you pass additional options to `./configure`.
* `MAKE` lets you override the command to use for `make`. Useful for specifying
  GNU make (`gmake`) on some systems.
* `MAKE_OPTS` (or `MAKEOPTS`) lets you pass additional options to `make`.
* `MAKE_INSTALL_OPTS` lets you pass additional options to `make install`.
* `RUBY_CONFIGURE_OPTS`, `RUBY_MAKE_OPTS` and `RUBY_MAKE_INSTALL_OPTS` allow
  you to specify configure and make options for buildling MRI. These variables
  will be passed to Ruby only, not any dependent packages (e.g. libyaml).

### Applying patches to Ruby before compiling

Both `rbenv install` and `ruby-build` support the `--patch` (`-p`) flag that
signals that a patch from stdin should be applied to Ruby, JRuby, or Rubinius
source code before the `./configure` and compilation steps.

Example usage:

```sh
# applying a single patch
$ rbenv install --patch 1.9.3-p429 < /path/to/ruby.patch

# applying a patch from HTTP
$ rbenv install --patch 1.9.3-p429 < <(curl -sSL http://git.io/ruby.patch)

# applying multiple patches
$ cat fix1.patch fix2.patch | rbenv install --patch 1.9.3-p429
```

### Checksum verification

If you have the `shasum`, `openssl`, or `sha256sum` tool installed, ruby-build will
automatically verify the SHA2 checksum of each downloaded package before
installing it.

Checksums are optional and specified as anchors on the package URL in each
definition. (All bundled definitions include checksums.)

### Package download mirrors

ruby-build will first attempt to download package files from a mirror hosted on
Amazon CloudFront. If a package is not available on the mirror, if the mirror
is down, or if the download is corrupt, ruby-build will fall back to the
official URL specified in the definition file.

You can point ruby-build to another mirror by specifying the
`RUBY_BUILD_MIRROR_URL` environment variable--useful if you'd like to run your
own local mirror, for example. Package mirror URLs are constructed by joining
this variable with the SHA2 checksum of the package file.

If you don't have an SHA2 program installed, ruby-build will skip the download
mirror and use official URLs instead. You can force ruby-build to bypass the
mirror by setting the `RUBY_BUILD_SKIP_MIRROR` environment variable.

The official ruby-build download mirror is sponsored by
[Basecamp](https://basecamp.com/).

### Package download caching

You can instruct ruby-build to keep a local cache of downloaded package files
by setting the `RUBY_BUILD_CACHE_PATH` environment variable. When set, package
files will be kept in this directory after the first successful download and
reused by subsequent invocations of `ruby-build` and `rbenv install`.

The `rbenv install` command defaults this path to `~/.rbenv/cache`, so in most
cases you can enable download caching simply by creating that directory.

### Keeping the build directory after installation

Both `ruby-build` and `rbenv install` accept the `-k` or `--keep` flag, which
tells ruby-build to keep the downloaded source after installation. This can be
useful if you need to use `gdb` and `memprof` with Ruby.

Source code will be kept in a parallel directory tree `~/.rbenv/sources` when
using `--keep` with the `rbenv install` command. You should specify the
location of the source code with the `RUBY_BUILD_BUILD_PATH` environment
variable when using `--keep` with `ruby-build`.


## Getting Help

Please see the [ruby-build wiki][wiki] for solutions to common problems.

[wiki]: https://github.com/rbenv/ruby-build/wiki

If you can't find an answer on the wiki, open an issue on the [issue
tracker](https://github.com/rbenv/ruby-build/issues). Be sure to include
the full build log for build failures.
