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Regular Expressions are important for us. We use them a lot, mostly because it’s such a powerful tool. So our puppet recipes contain several regsubst calls too. One problem is usually that regex can be fairly complex and you’d like a nice way to check it out. After some talk on IRC (#puppet on freenode), monachus gave me some tips for this. Simply use the interactive Ruby shell, irb, for this.
Now, I wanted to check whether a certain string ended in “:ssl” or not. I tested my regex replacement as follows:
$ irb >> s1="www.kumina.nl:ssl" => "www.kumina.nl:ssl" >> s2="www.kumina.nl" => "www.kumina.nl" >> s1.sub(/.*:(ssl)$/, "\\1") => "ssl" >> s2.sub(/.*:(ssl)$/, "\\1") => "www.kumina.nl" >>
From this I gathered that the resulting regsubst call would be something like this:
if regsubst($name, '.*:(ssl)$', '\1') == "ssl" { ... do stuff ... }
Awesome! Now, if you want to try out a global replace, instead of sub, use gsub.
If you want to use regex in your selector, you can simply use egrep on the commandline, like so:
echo "foo" | egrep "foo|bar"
You can also try it in irb, with the following:
>> a = "foo"
=> "foo"
>> a.match("foo|bar")
=> #<MatchData "foo">
>> b = "beastieboys"
=> "beastieboys"
>> b.match("foo|bar")
=> nil
>>
Hope this helps someone!