How to rewrite python script output in terminal?

Question

I have a python script and I want to make it display a increasing number from 0 to 100% in the terminal, I know how to print the numbers on the terminal but how can I "rewrite" them so 0 turns into 1, 1 into 2, and so on until 100?

Answer 1

This recipe here should prove useful. Using that module as tc, the following code does what you want:

from tc import TerminalController
from time import sleep
import sys

term = TerminalController()

for i in range(10):
    sys.stdout.write("%3d" % i)
    sys.stdout.flush()
    sleep(2)
    sys.stdout.write(term.BOL + term.CLEAR_EOL)

The recipe uses terminfo to get information about the terminal and works in Linux and OS X for a number of terminals. It does not work on Windows, though. (Thanks to piquadrat for testing, as per the comment below).

Edit: The recipe also gives capabilities for using colours and rewriting part of the line. It also has a ready made text progress bar.

Answer 2

Printing a carriage return (\r) without a newline resets the cursor to the beginning of the line, making the next print overwriting what's already printed:

import time
import sys
for i in range(100):
    print i,
    sys.stdout.flush()
    time.sleep(1)
    print "\r",