What does “\r” do in the following script?

Question

I am using following script to reboot my router using Telnet:

#!/usr/bin/env python

import os
import telnetlib
from time import sleep

host = \"192.168.1.1\         


        

Answer 1

\r is the ASCII Carriage Return (CR) character.

There are different newline conventions used by different operating systems. The most common ones are:

• CR+LF (\r\n);
• LF (\n);
• CR (\r).

The \n\r (LF+CR) looks unconventional.

edit: My reading of the Telnet RFC suggests that:

1. CR+LF is the standard newline sequence used by the telnet protocol.
2. LF+CR is an acceptable substitute:

The sequence "CR LF", as defined, will cause the NVT to be positioned at the left margin of the next print line (as would, for example, the sequence "LF CR").