Thanks Rick; I put your answer together with Alan's and I think I get a satisfying answer. On Fri, 2007-08-24 at 15:09 -0700, Rick Stevens wrote: > On Fri, 2007-08-24 at 17:42 -0400, William Case wrote: > > Hi; > > > > This question is meant as a Friday afternoon to a Sunday evening > > discussion. It is not rush; but I have been unable to discover an answer > > to what seems to me a basic question on how my computer works. > > > > > [snip] > Well, it's simple. The intent of text editors, word processors and the > like is that whatever you type in gets saved in the file. In *nix-ish > operating systems (Linux, Unix, MacOS, etc.), the RETURN or ENTER key is > denoted by a single character in the file. We call this the "newline" > character, which is the hexadecimal value 0x0a. In ASCII parlance, > that's the "LF" or "linefeed" character. The LF character can also > be entered by holding down the "CTRL" key and pressing "j" (also > sometimes called "control-J"). > > In Windows-type stuff (DOS, Windows, CP/M, etc.), the ENTER key is > denoted by a two character sequence, the hex value 0x0d (ASCII "CR" or > "carriage return"), followed by the hex value 0x0a (ASCII "LF" or > "linefeed" again). We call this sequence the "CRLF" sequence. Note > that the "CR" character can also be entered by holding down the "CTRL" > key and pressing "m", which is why it's sometimes called "control-M". > > (ADDITIONAL INFO: The hex value of "m" is "0x4d" and that of "j" is > 0x4a. Holding down the CTRL key inhibits the generation of bit 6 or > the value of 0x40, so CTRL-M generates 0x0d instead of 0x4d. Easy.) > > So much for text editors, word processors and the like. Now, when > you're at a command prompt or other program requesting input (remember > that the command prompt is the shell program asking for input), the > RETURN (or ENTER) key signals the end of user input and the program then > processes that according to whatever the program is supposed to do. > > Does that clarify things? > To re-summarize, the meaning of RET is established by the program being used. The program can create it's own meaning for RET; or use a standardized meaning according to what has been bound to the keymap the program is using, or redefine the keymap it uses to bind one or another meaning to a key press or event. -- Regards Bill
