To: Ikegami & Oko1, I'm not sure why you couldn't run the code

heh? I showed it does run in 5.10. my $_ is a feature introduced in 5.10.

I can't find the -le 'switch' Ikegami typed,

-l sets $\ to "\n".
-e causes the following value to be treated as a Perl code to execute.
See perlrun