rubyの正規表現で文字列抽出

matchを使うと正規表現で文字列を抽出できる

hoge = 'ip = 255.255.255.255'
ip = hoge.match(/ip = (\d+\.\d+\.\d+\.\d+)/)[1]
puts ip
$ ruby -e "hoge = 'ip = 255.255.255.255'; ip = hoge.match(/ip = (\d+\.\d+\.\d+\.\d+)/)[1]; puts ip"
255.255.255.255