rbenv

One option for Ruby dev environment manager (RVM is the other). rbenv works with Bundler to manage dependency versions and versions for Ruby AND Rails.

• rbenv is lighter than rvm
• does not include mechanisms to install ruby implementations
• manages multiple Ruby environments, allowing quick switches between implementations, locally or system-wide

How It Works

Uses shim executables injected into your PATH, to determine which ruby installation to pass commands to

• ~/.rbenv/shims is added in front of the PATH
• through rehashing rbenv maintains shims in that directory to match every Ruby command across every installation of Ruby
  • (commands like irb, gem, rake, rails, ruby)
• Shims are executables that pass commands to rbenv
  • Searches PATH for executable (like rake)
  • Finds rbenv shim named rake at the beginning of PATH (in shims directory)
  • Run the shim named rake which passes the command along to rbenv

Choosing the Ruby Version

After shim is executed, rbenv determines which ruby version to use

1. the RBENV_VERSION env variable, if set
   • rebenv shell command lets you specify this
2. the first .ruby-version file found by searching the directory of the script being run
3. the first .ruby-version file found by searching the current working directory, then parent directories
   • rbenv local to edit this
4. The global ~/.rbenv/version, defaulting to system ruby
   • rbenv global to edit

Ruby installations are found under ~/.rbenv/versions/1.8.7-p371 for example