Set to 1 to do multi-line matching within a string, 0 to tell Perl that it can assume that strings contain a single line, for the purpose of optimizing pattern matches. Pattern matches on strings containing multiple newlines can produce confusing results when
$* is 0. Default is 0. (Mnemonic: * matches multiple things.) This variable influences the interpretation of only
$. A literal newline can be searched for even when
$* == 0.
$* is deprecated in modern Perl, supplanted by the
/m modifiers on pattern matching.