my $re_single = qr/
    (?:\A|[\r\n]) # either the start of text or newline
    (
        [^\r\n]* # any non-newlines
        (?:\z|(?:\r\n|\n\r|\r|\n)\z) # last newline or eof
    )
/xs;

sub Last_N_Lines {
    my ( $str, $n ) = @_;

    my $nless = ( $n - 1 );

    my $re_multiple = qr/
        (?:\A|[\r\n]) # either the start of text or newline
        (
            (?:
                [^\r\n]*
                (?:\r\n|\n\r|\r|\n)
            ){0,$nless}
        ) # have to enclose above so it all goes into $1
        (
            [^\r\n]*
            (?:\z|(?:\r\n|\n\r|\r|\n)\z) # last nl or eof
        )
    /xs;

    if ( $n > 1 ) {
        if ( $str =~ m/$re_multiple/ ) {
            return( "$1$2" );
        } else {
            return( "" );
        }
    }

    if ( $str =~ m/$re_single/ ) {
        return( $1 );
    } else {
        return( "" );
    }
}