Daemon script - sh: unknown operand; arithmetic syntax error - shell

Question

I might be blind, but I can't find the errors my script got, maybe you guys got better eyes than me :). I use a busybox compiled linux on a embedded system, Kernel 4.18.0. I found the base script here: Gist-Template
the following error is at "start":
./daemon: line 195: arithmetic syntax error
when I try "stop" these messages appear, but i dont see a unknown operand at line 0:
sh: 0: unknown operand
* Stopping Monitoring
my script:
#!/bin/sh
daemonName="Monitoring"
pidDir="."
pidFile="$pidDir/$daemonName.pid"
pidFile="$daemonName.pid"
logDir="."
# To use a dated log file.
# logFile="$logDir/$daemonName-"`date +"%Y-%m-%d"`".log"
# To use a regular log file.
logFile="$logDir/$daemonName.log"
# Log maxsize in KB
logMaxSize=1024 # 1mb
runInterval=300 # In seconds
doCommands() {
# This is where you put all the commands for the daemon.
echo "Running commands."
}
############################################################
# Below are the command functions
############################################################
hw_temp() {
cpu_temp=$(sensors|grep CPU|awk '{print $3}'|awk '{print ($0-int($0)<0.499)?int($0):int($0)+1}')
env_temp=$(sensors|grep ENV|awk '{print $3}'|awk '{print ($0-int($0)<0.499)?int($0):int($0)+1}')
pcb_temp=$(sensors|grep PCB|awk '{print $3}'|awk '{print ($0-int($0)<0.499)?int($0):int($0)+1}')
echo "$cpu_temp $env_temp $pcb_temp" >> /opt/monitoring/bla
}
############################################################
# Below is the skeleton functionality of the daemon.
############################################################
myPid=`echo $$`
setupDaemon() {
# Make sure that the directories work.
if [ ! -d "$pidDir" ]; then
mkdir "$pidDir"
fi
if [ ! -d "$logDir" ]; then
mkdir "$logDir"
fi
if [ ! -f "$logFile" ]; then
touch "$logFile"
else
# Check to see if we need to rotate the logs.
size=$((`ls -l "$logFile" | cut -d " " -f 8`/1024))
if [[ $size -gt $logMaxSize ]]; then
mv $logFile "$logFile.old"
touch "$logFile"
fi
fi
}
startDaemon() {
# Start the daemon.
setupDaemon # Make sure the directories are there.
if [[ `checkDaemon` = 1 ]]; then
echo " * \033[31;5;148mError\033[39m: $daemonName is already running."
exit 1
fi
echo " * Starting $daemonName with PID: $myPid."
echo "$myPid" > "$pidFile"
log '*** '`date +"%Y-%m-%d"`": Starting up $daemonName."
# Start the loop.
loop
}
stopDaemon() {
# Stop the daemon.
if [[ `checkDaemon` -eq 0 ]]; then
echo " * \033[31;5;148mError\033[39m: $daemonName is not running."
exit 1
fi
echo " * Stopping $daemonName"
log '*** '`date +"%Y-%m-%d"`": $daemonName stopped."
if [[ ! -z `cat $pidFile` ]]; then
kill -9 `cat "$pidFile"` &> /dev/null
fi
}
statusDaemon() {
# Query and return whether the daemon is running.
if [[ `checkDaemon` -eq 1 ]]; then
echo " * $daemonName is running."
else
echo " * $daemonName isn't running."
fi
exit 0
}
restartDaemon() {
# Restart the daemon.
if [[ `checkDaemon` = 0 ]]; then
# Can't restart it if it isn't running.
echo "$daemonName isn't running."
exit 1
fi
stopDaemon
startDaemon
}
checkDaemon() {
# Check to see if the daemon is running.
# This is a different function than statusDaemon
# so that we can use it other functions.
if [ -z "$oldPid" ]; then
return 0
elif [[ `ps aux | grep "$oldPid" | grep "$daemonName" | grep -v grep` > /dev/null ]]; then
if [ -f "$pidFile" ]; then
if [[ `cat "$pidFile"` = "$oldPid" ]]; then
# Daemon is running.
# echo 1
return 1
else
# Daemon isn't running.
return 0
fi
fi
elif [[ `ps aux | grep "$daemonName" | grep -v grep | grep -v "$myPid" | grep -v "0:00.00"` > /dev/null ]]; then
# Daemon is running but without the correct PID. Restart it.
log '*** '`date +"%Y-%m-%d"`": $daemonName running with invalid PID; restarting."
restartDaemon
return 1
else
# Daemon not running.
return 0
fi
return 1
}
loop() {
# This is the loop.
now=`date +%s`
if [ -z $last ]; then
last=`date +%s`
fi
# Do everything you need the daemon to do.
doCommands
# Check to see how long we actually need to sleep for. If we want this to run
# once a minute and it's taken more than a minute, then we should just run it
# anyway.
last=`date +%s`
# Set the sleep interval
if [[ ! $((now-last+runInterval+1)) -lt $((runInterval)) ]]; then
sleep $((now-last+runInterval))
fi
# Startover
loop
}
log() {
# Generic log function.
echo "$1" >> "$logFile"
}
###############################################################
# Parse the command.
###############################################################
if [ -f "$pidFile" ]; then
oldPid=`cat "$pidFile"`
fi
checkDaemon
case "$1" in
start)
startDaemon
;;
stop)
stopDaemon
;;
status)
statusDaemon
;;
restart)
restartDaemon
;;
*)
echo "Error: usage $0 { start | stop | restart | status }"
exit 1
esac
exit 0