preceding example showed how you can redirect a standard stream from
within your program. But what if later in your program you wanted to
restore the standard stream to its original state?
By using the standard C library functions named dup() and fdopen(),
you can restore a standard stream such as stdout to its original
The dup() function duplicates a file handle. You can use the dup()
function to save the file handle corresponding to the stdout
The fdopen() function opens a stream that has been duplicated with
the dup() function.