If you're on a Mac with homebrew installed, you may simply brew install ry and follow the instructions.

Otherwise, install the files from the repo to your favorite prefix (I use ~/.local, which is the default).

git clone git://github.com/jneen/ry
cd ry
PREFIX=$HOME/.local make install

and add the following lines to your bashrc (or zshrc):

# If you're using the default ~/.local prefix,
# make sure ~/.local/bin is on your $PATH.
export PATH="$HOME/.local/bin:$PATH"
eval "$(ry setup)"

or, if you don't like eval, you can do it manually:

export PATH="$PREFIX/lib/ry/current/bin:$PATH"

For ZSH completion, see this.

If you want to specify a different directory for installing rubies:

# rubies are installed into $RY_PREFIX/lib/ry/rubies
# set RY_RUBIES for an alternate location
export RY_RUBIES="$HOME/.rubies"

Ry is a bit different from other version managers. The major design goal of ry is to be explicit, unobtrusive, and easy to query. In the vein of the n package manager for node, there are no subshells, and the only thing it needs to add to your environment is a single entry to your $PATH (also tab completion if you like). For example, here's how you create a new installation:

ry install http://ftp.ruby-lang.org/pub/ruby/1.9/ruby-1.9.3-p125.tar.gz mri-1.9.3

This creates an installation of Ruby called mri-1.9.3 using the tarball from ruby-lang.org. To switch to this ruby, use

ry use mri-1.9.3 # or: ry mri-1.9.3

Want to use a custom commit?

ry install https://github.com/ruby/ruby/tarball/<hash> mri-custom

If you have ruby-build installed, you can use it very easily with ry:

ry install 1.9.3-p125

Because ry use changes a symlink, that ruby is globally activated across all shells. To use a shell-local ruby, simply set your $PATH to include that ruby's bin dir. The easiest way to do this is to use the ry fullpath <ruby> helper, which outputs a copy of your $PATH variable modified for use with ry.

export PATH="$(ry fullpath my-cool-ruby)"

You can activate this automatically with something like direnv.

For more information, see ry help.

All of the magic is in the bash script bin/ry. Here are a couple of bash features I use that aren't common elsewhere:

• Poor man's namespacing - the character : is a perfectly valid character to use in a bash function's name. All of ry's subcommands are implemented as functions looking like ry::foo. At the bottom of the file is the function ry which essentially delegates to ry::$1 - so to add a new subcommand, all you need to do is define the bash function and document it in ry::usage.

• Piping from heredocs is awesome. The syntax cmd <<<"$variable" runs cmd with stdin as the content of $variable. I use this extensively, and you should too.