$ perl -MO=Deparse -0lpe 's/2/4/gs'
BEGIN { $/ = "\000"; $\ = "\000"; }
...
$ perl -MO=Deparse -l0pe 's/2/4/gs'
BEGIN { $/ = "\n"; $\ = "\000"; }
...
$ perl -MO=Deparse -lp0e 's/2/4/gs'
BEGIN { $/ = "\000"; $\ = "\n"; }
...
$ perl -MO=Deparse -l1p0e 's/2/4/gs'
BEGIN { $/ = "\000"; $\ = "\001"; }
...

##</code><code>##

$ perl -MO=Deparse -0777 -lpe 's/2/4/gs'
BEGIN { $/ = undef; $\ = ""; }
...