I thought the following extract from Dave Williams' excellent
(but a somewhat dated) shareware "book", DOSREF, would
be of interest, regarding STDOUT... I don't think Ralf Brown's
interrupt list has this information, BTW ...
You can get a demo version (first few chapters) of DOSREF
at : http://www.darklogic.org/fdos/ftp/dosref/
Extract follows (not sure if this will come out right, if not, just
download that demo, see Chapter.007 ... OK? :-) :
Special File Handles ............................................ 7**4
DOS reserves five special file handles for use by itself and
applications programs. They are:
|-----------------------------------------------------------------------|
| 0000h | STDIN | standard input device (input can be redirected) |
| 0001h | STDOUT | standard output device (output can be redirected) |
| 0002h | STDERR | standard error output device (output cannot be |
| | | redirected) |
| | | NOTE: DOS opens STDERR for both writing and reading. |
| | | Since STDIN can be redirected, using STDERR to read |
| | | the keyboard is a reliable way to ensure that your |
| | | program is actually |
| | | reading the keyboard, if that's what you want to do. |
| 0004h | STDAUX | standard auxiliary device |
| 0005h | STDPRN | standard printer device (PRN, normally LPT1) |
|-----------------------------------------------------------------------|
These handles are predefined by DOS and can be used by an
application program. They do not need to be opened by a program,
although a program can close these handles. STDIN should be treated
as a read-only file, and STDOUT and STDERR should be treated as write-
only files. STDIN and STDOUT can be redirected. All handles
inherited by a process can be redirected, but not at the command line.
[BTW, I was puzzled by that last line at first, but all
I think it is saying, is just that only STDIN and STDOUT
can be redirected via the command line ... Joe]
Regards to all,
Joe.
