outputs "Locked" & "Unlocked" + `date` every time the [fedora+plasma] machine's screen is locked/unlocked. Add to startup script like `nohup lockMonitor.sh >>locklog.txt &`

lockMonitor.sh

#!/bin/bash

#prints out, among other things;
#      string "org.kde.screensaver"
#transform it to 'org.kde.screensaver'
service=$(\
	dbus-send \
		--session \
		--dest=org.freedesktop.DBus \
		--type=method_call \
		--print-reply \
		/org/freedesktop/DBus org.freedesktop.DBus.ListNames \
	| grep -o '[^"]*.screensaver'
)

#prints out, among other things;
#method bool org.freedesktop.ScreenSaver.SetActive(bool e)
#transform it to 'org.freedesktop.ScreenSaver'
interface=$(
	qdbus \
		$service /ScreenSaver \
	| grep -oP '[^ ]*(?=.SetActive)'
)

path='/ScreenSaver'

#monitor it with a while loop
dbus-monitor "type='signal',interface='$interface',member='ActiveChanged',path='$path'" \
| while read -r line; do
	#ignore the metadata and pull the 'boolean <true/false>' line
	read line

	#check if it is set to true
	if echo $line | grep -q 'true'; then
		echo "Locked at $(date)"
	else
		echo "Unlocked at $(date)"
	fi
done