Perhaps your problem is because there is no "while" statement on your "do" block ... you may want this kind of structure, roughly:

for (@_) {
   do {
      # stuff to do here
   } while (/\.dat/);
}
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...Or, if you aren't trying for a do/while loop, just testing for ".dat" in the string, maybe you want:

for (@_) {
   if (/\.dat/) {
      # stuff to do here
   }
}
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You may also want to replace /\.dat/ with /(\.dat)$/ to make sure that's the file extension, so "test.dat.old" wouldn't be a match.

Update: I thumbed through the Camel and discovered there is a "do BLOCK" form I wasn't aware of, so my answer may be way off from what you're looking for.

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