> $_ automatically was assigned the last line 

That's a special DWIM magic within the while condition only!

while (<>) {

... which is Perl shorthand for the more explicitly written version: ...

while (defined($line = <ARGV>)) {

Cheers Rolf
(addicted to the Perl Programming Language and ☆☆☆☆ :)
Je suis Charlie!

In reply to Re^5: uninitialized value $_ by LanX
in thread uninitialized value $_ by Anonymous Monk

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