shutdown a box if it hasn't been logged into for a while

idle_kill.py

#!/usr/bin/env python3

import getpass
import re
import time
import subprocess
import sys

MIN_UPTIME = 1800  # 30 minutes of uptime required before autokilling
TIME_DELTA = 21600 # 6 hours of uptime max before autokilling

LOGIN_REGEXP=r"(\w+)\s+(pts/\d)\s+([\da-f:.]+)\s+([-+T:\d]+)\s+-?\s*(still logged in|[-+T:\d]+)"

def get_last_login(username=None):
    """Get the last login of the specified user. Defaults to the running user."""
    if username == None:
        username = getpass.getuser()
    proc = subprocess.run(["last", "--time-format", "iso", username], stdout=subprocess.PIPE, encoding="utf-8")
    if proc.returncode != 0:
        sys.exit(1)
    logins = proc.stdout.split("\n")
    for line in logins:
        if not line.startswith(username):
            # ignore lines that don't start with the username
            continue
        else:
            matches = re.match(LOGIN_REGEXP, line)
            if matches == None:
                continue
            else:
                # got a match
                login_end_time   = matches.groups()[4]
                if login_end_time == "still logged in":
                    return -1
                else:
                    last_time = time.mktime(time.strptime(login_end_time, "%Y-%m-%dT%H:%M:%S%z"))
                    return last_time

def get_uptime():
    """Get system uptime."""
    with open('/proc/uptime', 'r') as f:
        uptime_seconds = float(f.readline().split()[0])
        return uptime_seconds


def main():
    uptime_sec = get_uptime()
    if uptime_sec < MIN_UPTIME:
        # do not do anything if we have not hit minimum uptime
        sys.exit(0)

    last_login_time = get_last_login()
    if last_login_time == -1:
        # someone is still logged in, do nothing
        sys.exit(0)

    now = time.time()
    if (now - last_login_time) > TIME_DELTA:
        # trigger shutdown, since we are past the time delta
        subprocess.Popen(["sudo", "shutdown", "-h", "now"])

if __name__ == "__main__":
    main()