cheat sheets.

Install a gem

  gem install [gem name]

Update to latest Rubygems (if any):

  gem update --system

Search for a gem:

  gem query --remote --name [regular expession]

Get list of outdated gems and update as necessary:

  gem outdated

Clean up outdated gems:

  gem clean

List installed gems by last access time:

  gem stale

Current Local Gem Repository:

  gem environment

  or

  ruby -rrubygems -e"puts Gem.path"

Discover Dependency for a Gem:

  gem dependency [gem name]

Don't generate Ri and RDoc when installing gems:

  gem install [gem name] --no-ri --no-rdoc

  to set this as default behavior:

  echo "gem: --no-ri --no-rdoc" >> ~/.gemrc

Uninstalling:

  gem uninstall [gem name]

  if that fails with something like:
  ERROR:  While executing gem ... (Gem::InstallError)
      Unknown gem [gem name]
  then do this...

  gem list -d [gem name]
  gem uninstall --install-dir [install directory] [gem name]

Add a repository for remote gems:

  gem sources -a [repository url]