🚀 go-pugleaf

In article <1426@wet.UUCP> naga@wet.UUCP (Peter Davidson) writes:
>Let's say X.EXE is a program written in (Microsoft) C which
>calls printf() to output to the monitor.  Invoking X using
>X > PRN (or some file) redirects output to the printer (or file).
>Suppose that X does something (such as writing directly to video RAM)
>which it would not like to do if output has been redirected as above?
>How can it tell?  One solution is: Use printf() to output a charactr
>and then peek in the video RAM to see if the character went there
>(if so, no redirection).  The disadvantage is that, if redirection
>is in effect, a character (perhaps only a space) is sent to the
>printer (or file).  Is there a more elegant way to tell whether
>output has been redirected? 

That's not too elegant a solution: there is no guarantee that printf will
put the character in a specific memory location, and if I/O is redirected,
that character may already be on the screen. In C the easiest way to determine
if I/O has been redirected is to call isatty(fileno(stdout)) this returns
non-zero if the file descriptor associated with stdout is a character device.
The problem with this is the redirection may be associated with another
character device (AUX, PRN, etc). Is there an easy way to do THIS?

Cheers! 
Steve

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