Minor code point, to save yourself some typing take advantage of variable interpolation inside double-quoted strings.

my $line = $_;

if($line =~ s/^.+\/\.(.*)$/$1/)
 { print ". extension $line\n"; }
elsif ( $line =~ s/^.+\.(.*)$/$1/)
 { print "Extension $line\n"; }
[download]

Note that no interpolation takes place inside single-quoted strings.

Cheers,

JohnGG