KDE screen lock log?

When the screen is locked in KDE (my specific version is Kubuntu but hopefully this is something that is generic Linux), is the event logged? If so where would I look to find it?

Use D-Bus to get lockscreen's actived/deactived signals. The name of the screen saver service will vary from system to system. In general, KDE uses org.freedesktop.ScreenSaver and Gnome uses org.gnome.ScreenSaver. This cannot be relied upon though, for example, Mint uses org.cinnamon.ScreenSaver.

Helpful Commands

These assume that your screen saver is org.freedesktop.ScreenSaver and your DBus service is org.freedesktop.DBus. You may need to adjust this for other systems. Use the following information to find out what your system uses:

• To get a list of the dbus services available in your current session, use:

  dbus-send --session --dest=org.freedesktop.DBus --type=method_call --print-reply /org/freedesktop/DBus org.freedesktop.DBus.ListNames
  

  Add |grep screensaver to the end if you just want the screen saver services available.

• To get a list of the commands supported by your screen saver service, use:

  qdbus org.freedesktop.ScreenSaver /ScreenSaver
  

• To invoke a command, use:

  dbus-send --session --dest=org.freedesktop.ScreenSaver --type=method_call --print-reply --reply-timeout=20000 /org/freedesktop/ScreenSaver org.freedesktop.ScreenSaver.SetActive boolean:true
  

  Where SetActive was listed in the list of supported commands and takes a boolean value.

• To monitor a service:

  dbus-monitor --session "type='signal',interface='org.freedesktop.ScreenSaver'"
  

Automation

Now that you understand how your system works, you can use a python script to log this activity into a file:

#!/usr/bin/env python
from datetime import datetime
import os
import pwd
import subprocess
import time

LOG_FILE = os.path.expanduser('~/hours_log.csv')


cmd = subprocess.Popen(["dbus-monitor \"type='signal',interface="
                        "'org.freedesktop.ScreenSaver'\""], shell=True,
                       stdout=subprocess.PIPE)

running = 0
while 1:
    time.sleep(0.1)
    if running:
        output = cmd.stdout.readline()
        status = 'unlocked' if 'true' in output else 'locked'
        new_line = "{time} {user} {status} the screen\n".format(
            time=datetime.now().ctime(),
            user=pwd.getpwuid(os.getuid())[0],
            status=status
        )
        with open(LOG_FILE, 'a') as f:
            f.write(new_line)

        running = 0
    line = cmd.stdout.readline()
    if "ActiveChange" in line and 'org.freedesktop.ScreenSaver' in line:
        running = 1

[ Source: logging-lock-screen-events ]