Integer File Descriptor “0” in open()

Question

In Python 3, it is possible to open a file object using an \"integer file descriptor\" with the format:

stdout = open(1, \"w\")
stdout.write(\"Hello World\")         


        

Answer 1

> syntax is handled by the shell before python is invoked. It connects stdout to the given file, as 2> does for stderr and < does for stdin.

All that said, 0, 1, and 2 are file descriptors reserved for stdin, stdout, and stderr respectively (which is why 2> is the syntax to redirect stderr).

So 0 is a valid file descriptor, but one that is your stdin, which you're opening again for writing. This ends up writing to the terminal it seems, since that's where stdin was going to write.