NoPrinterShutdown

#!/bin/bash
# (c) 2020 Leif Sawyer
# License: GPL 3.0 (see https://github.com/akhepcat/)
# Permanent home:  https://github.com/akhepcat/Miscellaneous/
# Direct download: https://raw.githubusercontent.com/akhepcat/Miscellaneous/master/NoPrinterShutdown
# 

# Production values
WAIT=15
SLEEP=60
USBv=03f0
USBd=1c17

# Debugging overrides
# SLEEP=1
# WAIT=2
# USBd=1c16

PIDF=/run/NoPrinterShudown.pid

if [ -e $PIDF ]
then
	PIDp=$(pgrep --pidfile ${PIDF})
	if [ -n "${PIDp}" ]
	then
		# running, so exit
		exit 1
	else
		# not running, stale pidfile
		logger -t "usb-watchdog" "stale pidfile, removing"
		rm -f ${PIDF}
	fi
fi
echo $$ > $PIDF

Device=$(lsusb -d $USBv:$USBd)

if [ -n "${Device}" ]
then
	#We see the printer
	rm -f $PIDF
	exit 0
fi

# Else we don't see the printer, so we loop for 15 minutes, checking for the
# printer's return, otherwise we shut down.

logger -t "usb-watchdog" "Lost the printer, starting ${WAIT}m timer"

for timer in $(seq 1 $WAIT)
do

	Device=$(lsusb -d $USBv:$USBd)
	if [ -n "${Device}" ]
	then
	        #We see the printer has returned!
		logger -t "usb-watchdog" "Printer returned after ${WAIT}m. Aborting shutdown."
	        rm -f $PIDF
	        exit 0
	fi
	logger -t "usb-watchdog" "tic ${timer} of ${WAIT}"
	sleep $SLEEP
done

# We made it this far without seeing the printer return, so just shutdown

logger -t "usb-watchdog" "Printer off-line, activating shutdown."
rm -f $PIDF
/sbin/shutdown --poweroff --no-wall now