What is the use of '\b' (backspace)

Question

I\'m taking a Python class right now, and I just learned about the backspace character. Like newline (\\n), backspace is a special character with ASCII code 8. My teacher c

Answer 1

Maybe it helps to first understand what is happening there:

print() is writing to the standard output and it is writing everything there including the w and the backspace.

Now something has to display it. Most likely a terminal emulator.

What theoretically would happen is that the w was displayed and then deleted, but it was not flushed and was to fast for it to actually happen.

So real-life applications will almost always use \b at the beginning of the printed text.

I wrote a short example that will have a little spinner on a progress indicator. The example print "-" followed by "\b\\" (deleting the - and replacing it with \) followed by "\b|" (deleting the \ and replacing it with |) and so on.

That way - \ | / - \ | / looks like an animated rotating line.

#!/usr/bin/env python3
import time

spinner="\\|/-"
print ("----------\r", end='', flush=True)
for pos in range(10):
    print ("-", end='', flush=True)
    for spin in range(25):
        #here should be a break as soon as some task proceeded further
        time.sleep(0.1)
        print ("\b" + spinner[spin % 4], end='', flush=True)
    print ("\b*", end='', flush=True)
print ()

P.S.: A lot of existing programs use control characters like \b \r \033 to display a status line. Most popular is probably wget. I have also seen such output by at least one python script (although I cant remember which one any more)