Ruby method that shells out to git describe and formats results

gistfile1.rb

def get_tag_info(commit)
  info = `git describe --tags #{commit}`.chomp

  if info[/(.*)-(\d+)-g([a-z0-9]{7})/]
    matches = Regexp.last_match
    last_tag = matches[1]
    commits_since_tag = matches[2]
    noun = (commits_since_tag.to_i == 1) ? 'commit' : 'commits'
    "#{last_tag} + #{commits_since_tag} #{noun}"
  else
    info
  end
end