Not sure I completely understand, but does this do it for you? 
if (/^(foobar:((?!=gonk|\@).)+)/) {
  print "matched $1\n";
}

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That's your classic "inchworm" pattern, so it's not the fastest in the world.

-- Randal L. Schwartz, Perl hacker
Be sure to read my standard disclaimer if this is a reply.

update: Yeah, just like in real life, he changes the spec after I write the implementation. {grin}

And the spec is still broken:

I'm having problems working out how to perform the following regex. I want to match foobar:Xgonk where X is between 1 and 5 characters, and can be anything except 'gonk' (or the beginning of 'gonk') or '@'. I then want to remove gonk or @.
The last "or @" is spurious. There could never be an "@" there, since it has to have a trailing "gonk" where we stop.

In reply to Re: RegEx - match !foo followed by foo by merlyn
in thread RegEx - match !foo followed by foo by Melly

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