From: MonkeeSage <MonkeeSage@...>
Date: 2006-10-03T09:30:11+09:00
Subject: Re: regular expressions

Tom Allison wrote:
> So, how do you set a variable in a regular expression?

You have it right.

> Also, how would I match multiple lines?

You're right again with the //m. But you can't read line-by-line
(IO#each) and match across multiple lines without building some kind of
parser. It's usually better to just read the data into a single string
for multiline matches.

Input (multiline):
Received: from mail.papa.smurf (mail.papa.smurf [127.0.0.1])
by down@fraggle.roc

config = {'hostname' => 'down@fraggle.roc'}
line = $stdin.read
puts line if line =~ /^Received:.*by #{config['hostname']}/m

> I would much rather match something like:
>
> /^Received:.+?\s{4,}by #{config['hostname']}/sm
> because that will pick up the one Received header I want.
> I can write in Perl 5 regex but I'm not as familiar with Ruby's methods.

Input (single line):
Received: from mail.papa.smurf (mail.papa.smurf [127.0.0.1])    by
down@fraggle.roc

$stdin.each { |line|
  puts line if line =~ /^Received:.+?\s{4,}by #{config['hostname']}/
}

Regards,
Jordan