README.md

This is how I ensure a Python script is launched as root, and automatically call sudo to re-launch it as root if not.

I found it useful to check the parameters are valid before re-launching as root, so I don’t have to enter the sudo password if there is a problem with the parameters, or I just want the help message.

Note 1: os.execvp() replaces the running process, rather than launching a child process, so there's no need to exit afterwards.

Note 2: The extra "sudo" in the second parameter is required because Python doesn't automatically set $0 to sudo in the new process.

Example.py

import os
import sys
 
# At this point we may be running as root or as another user
# Check the parameters are valid - show an error if not
# Show the help message if requested
 
if os.geteuid() != 0:
    os.execvp("sudo", ["sudo"] + sys.argv)
 
# Now we are definitely running as root
# Make the changes to the system settings (e.g. Apache config)