People are confused about strings and lines. A string is a sequence of characters, a line can be two different things. If you consider the newline a line termin

People are confused about strings and lines. A string is a sequence of characters, a line can be two different things. If you consider the newline a line terminator, then a line is a sequence of non-newline characters - possibly zero - plus a newline. If there is no new-line at the end, then it is not a [complete] line. That is what POSIX uses. If you consider the newline a line separator, then a line is a sequence of non-newline characters - possibly zero. In either case, the content of the line ends before the newline, either because the newline terminates the line or because it separates the line from the next. [1] The semantics of ^ and $ is based on lines - whether single-line or multi-line mode. For string based semantics - which you could also think of as entire file if you are dealing with files - use \A and \Z or their equivalents. [1] Both interpretations have their merits. If you transmit text over a serial connection, it is useful to have a newline as line terminator so that you know when you received a complete line. If you put text into text files, it might arguably be easier to look at a newline as a line separator because then you can not have a invalid last line. On the other hand having line terminators in text files allows you to detect incompletely written lines.