in reply to Reading double lines at a time

Not to my knowledge

 $/ = undef ==> Read in entire file
 $/ = '' ==> Read by paragraphs
 $/ = 'c' ==> Read until 'c' is encountered

However, you can do something like this:

while(<FILE>){ $_ .= defined(my $temp = <FILE>)?$temp:''; #do whatever you want with $_ }