A line terminator is a one- or two-character sequence that marks the end of a line of the input character sequence. The following are recognized as line terminators:
A newline (line feed) character ('\n'),
A carriage-return character followed immediately by a newline character
("\r\n"),
A standalone carriage-return character ('\r'),
A next-line character ('\u0085'),
A line-separator character ('\u2028'), or
A paragraph-separator character ('\u2029').
If UNIX_LINES mode is activated, then the only line terminators recognized are newline characters.
The regular expression . matches any character except a line terminator
unless the DOTALL flag is specified.
By default, the regular expressions ^ and $ ignore line
terminators and only match at the beginning and the end, respectively, of the entire input
sequence. If MULTILINE mode is activated then ^ matches at the beginning of input
and after any line terminator except at the end of input. When in MULTILINE mode $ matches just before a line terminator or the end of
the input sequence.