@cancel, в подтверждение /1
In Ruby there is no multiline flag, regexps in Ruby are always in multiline mode. See advogato.org/person/fxn/diary/498.html for some gotchas regarding regexp flags in Perl vs Ruby.
In Ruby, you need to use \A and \z (or\Z) to match start and end of string.
Ruby won't prevent you shooting your foot.