winapi - How do I detect when output is being redirected?

Question

I have a Win32 application written in C that can have its console output via printf() redirected to a log file.

It would be nice if I could have my app. detect if it had been started with or without a redirect '>'.

Any ideas?

Answer 1

Tom, thanks for the input.

I did some experiments and found this works for me..

fpost_t pos ;

fgetpos (stdout, & pos) ;

When an application's output is being redirected to a file, fgetpos() sets 'pos' to zero. It makes sense since its freshly opened stderr for you. EDIT: Actually, the value returned may be a positive integer if text has already been redirected to the log/file. So in your code you'd have something like "if (pos >= 0) bfRedirected = TRUE ;"

When an application's output is not being redirected - it's going to the console device - not a file, so fgetpos() will set 'pos' to -1.