in reply to
grep flip flop (range operator)
What are you expecting to get with 1 .. /Q/?
The following code prints nothing as well:
Data::Dump::dd(1 .. /Q/);
If your match-list is empty, nothing matches, and nothing is printed.
However, this does not explain why the last command *does* print something :)
Edit: Upon further reading, it looks like the range operator isn't parsed in scalar context, as the following does print something:
perl -le " print for grep scalar 1 .. /Q/, @ARGV " a b c Q r s