Redirect Output in UNIX: How to Use freopen() to Print to Console

[ptabor]

So I'm using freopen to redirect output from stdout to a file... How do I redirect it back to the screen?

relevant code:

FILE *stream = freopen("data.txt", "w", stdout);

/* print stuff */




How the heck do I get the output stream to point to the console again?

 

[AlephZero]

On Unix, you can access "the screen" (and every other device) via a filename. /dev/tty is a good bet for what stdout was attached to.

freopen("/dev/tty",...) should work.

But this isn't a very polite thing to do, because stdout might have been redirected by the user.

Another idea would be something like this:

FILE *myfile;
FILE *datafile = fopen("data.txt"...);

Then do

myfile = stdout;
or
myfile = datafile;

(filp back and forth as often as you like)

and do all your I/O to myfile.

 

[ravenprp]

To redirect output back to the console, you can use the same freopen() function but with "stdout" as the file name instead of a specific file. This will redirect the output back to the standard output stream, which is typically the console.

So the relevant code would be:

FILE *stream = freopen("stdout", "w", stdout);

/* print stuff */

This will reset the standard output stream to the console and any subsequent output will be printed to the console. It is important to note that this will only work if the standard output stream has not been closed or redirected to a different file. If that is the case, you may need to use a different method to redirect the output back to the console.