I would actually suggest forgoing the loop altogether and using grep: 
my @FILES = grep { -f } readdir (TEMP);
foreach my $file (@FILES){
  open (F, $file) or warn "Couldn't open $file: $!" and next;
  my @matches = grep {  /$str/ }  <F>;
  close (F);
  next unless scalar @matches > 0;
  print join("\n", @matches); 
}

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Of course, that prints every matching line in the file, if you only want the first (evidenced by "last"), you could just use: 
print $matches[0], "\n";

[download]
And do you really want to use "die" in a loop? What if you can't open one file, but you can open the rest? Isn't "warn and next" more appropriate?

In reply to Re^2: Problem with regex by mpeever
in thread Problem with regex by nave448

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