$PROGRAM_NAME

$FORMAT_NAME

$\ The output record separator for the print operator. If defined, this value is printed after the last of print's arguments. Default is

$FORMAT_LINES_LEFT

$^D The current value of the debugging flags. May be read or set. Like its command-line equivalent, you can use numeric or symbolic values

$RS

%ENV The hash %ENV contains your current environment. Setting a value in

$ORS

%! Each element of %! has a true value only if $!

IO::Handle->format_formfeed(EXPR)