@ok = `grep @opts '$search_string' @filenames`;
You have to do this:
my @ok = ();
if (open(GREP, "-|")) {
while (<GREP>) {
chomp;
push(@ok, $_);
}
close GREP;
} else {
exec 'grep', @opts, $search_string, @filenames;
}
Just as with system, when you exec a list, so no
shell escapes happen.