wget https://github.com/Grum1in/grumlin-docs/releases/download/1.0/checker.sh
chmod 755 ./checker.sh

LISK_DIR="$(pwd)/lisk-Linux-x86_64" (delete $(pwd) if you download this script to not working user directory)
PUBLICKEY=ff8aa63ae5eeb6cd866b615934163c1a94d25819a85b93856f1cdbcf439005c4
NODEIP=89.40.125.40
EMAIL=lisk.grumlin@gmail.com
APIPORT=7000(in mainnet will be 8000)

bash checker.sh installsmtp

bash checker.sh tunesmtp

bash checker.sh autostart

bash checker.sh logs

#!/bin/bash

# file
DAT_FILE="$(pwd)/checker.data"
LOG_FILE="$(pwd)/checker.log"
LISK_DIR="$(pwd)/lisk-Linux-x86_64"

# public key and IP your node
PUBLICKEY=ff8aa63ae5eeb6cd866b615934163c1a94d25819a85b93856f1cdbcf439005c4
DATE=`date "+%F %H:%M:%S"`
NODEIP=89.40.125.40
EMAIL=lisk.grumlin@gmail.com
APIPORT=7000

exec_check() {
# get list of IPs of peers(9 ps)
[[ $(curl -s 'http://127.0.0.1:'$APIPORT'/api/peers?') =~ \"success\":([[:lower:]]+),.*\
\"ip\":\"([[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+)\",\"port\":[[:digit:]]+,\"state\":2.*\
\"ip\":\"([[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+)\",\"port\":[[:digit:]]+,\"state\":2.*\
\"ip\":\"([[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+)\",\"port\":[[:digit:]]+,\"state\":2.*\
\"ip\":\"([[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+)\",\"port\":[[:digit:]]+,\"state\":2.*\
\"ip\":\"([[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+)\",\"port\":[[:digit:]]+,\"state\":2.*\
\"ip\":\"([[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+)\",\"port\":[[:digit:]]+,\"state\":2.*\
\"ip\":\"([[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+)\",\"port\":[[:digit:]]+,\"state\":2.*\
\"ip\":\"([[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+)\",\"port\":[[:digit:]]+,\"state\":2.*\
\"ip\":\"([[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+)\",\"port\":[[:digit:]]+,\"state\":2.* ]]
if [ ! -z ${BASH_REMATCH[1]} ] && [ ${BASH_REMATCH[1]} == true ]; then
	for IPs in 2 3 4 5 6 7 8 9 10; do
		IPDELEGATES[$IPs - 1]=${BASH_REMATCH[$IPs]}
	done
fi

# get local height
[[ $(curl -s 'http://127.0.0.1:'$APIPORT'/api/loader/status/sync') =~ \"success\":([[:lower:]]+),.*\"height\":([[:digit:]]+) ]]
MYHEIGHT=${BASH_REMATCH[2]}
let "MYHEIGHT+=5"

# get system param
FREEMEM=`head /proc/meminfo | grep MemFree | awk '{ print $2 }'`
CPULOAD=`ps aux | awk '{s += $3} END {print s "%"}'`

# restart client if free memory less than ~50 MB
if [ $FREEMEM -lt 50000 ]; then
	echo $DATE "Restart miner! Memory is low! MemFree is" $FREEMEM >> "$LOG_FILE"
        /bin/bash $LISK_DIR/lisk.sh restart
        exit 0
fi

MAXHEIGHT=0

# find the biggest height in peers
for IP in ${IPDELEGATES[@]}; do
        [[ $(curl -s 'http://'$IP':'$APIPORT'/api/loader/status/sync') =~ \"success\":([[:lower:]]+),.*\"height\":([[:digit:]]+) ]]
	if [ ! -z ${BASH_REMATCH[1]} ] && [ ${BASH_REMATCH[1]} == true ] && [ ${BASH_REMATCH[2]} -gt $MAXHEIGHT ]; then
		MAXHEIGHT=${BASH_REMATCH[2]}
		MAXHEIGHTPEER=$IP
        fi
done

# MAIN CODE
# check our node by peer of the best hieght
[[ $(curl -s 'http://'$MAXHEIGHTPEER':'$APIPORT'/api/delegates/get?publicKey='$PUBLICKEY) =~ \"success\":([[:lower:]]+),.*\"missedblocks\":([[:digit:]]+),.*\"rate\":([[:digit:]]+),\"productivity\":\"([[:digit:]]+\.[[:digit:]]+)\" ]]

SUCCESS=${BASH_REMATCH[1]}
MISSED=${BASH_REMATCH[2]}
RATE=${BASH_REMATCH[3]}
PRODUCTIVITY=${BASH_REMATCH[4]}

if [ -f "$DAT_FILE" ]; then
	MISSEDNOW=$(sed -n '1p' "$DAT_FILE")
	elif [ ! -z $MISSED]; then echo $MISSED > "$DAT_FILE"
	else echo 0 > "$DAT_FILE"
fi

# check node by fork
tail -n 1000 $LISK_DIR/logs.log | grep "\"cause\":3" > /dev/null 2>&1
if [ $? = 0 ]; then
	echo "Node forked! Node" $NODEIP "rebuilded! Current height is" $MAXHEIGHT "* Node height is" $MYHEIGHT "* MemFree is" $FREEMEM "* CPU load is" $CPULOAD | mail -v -s "Missed block by forging!" $EMAIL > /dev/null 2>&1
	echo $DATE "Node forked! Node rebuilded! Current height is" $MAXHEIGHT "* Node height is" $MYHEIGHT "* MemFree is" $FREEMEM "* CPU load is" $CPULOAD >> "LOG_FILE"
	/bin/bash $LISK_DIR/lisk.sh rebuild
fi

if [ ! -z $SUCCESS ] && [ $SUCCESS == true ]; then
        if [ $MISSEDNOW -lt $MISSED ]; then
                #curl -s 'http://sms.ru/sms/send?api_id=2549E81F-24F5-0990-D873-4911358B12A3&to=375295180951&text=Missed+block!+Check+node!' > /dev/null 2>&1
		echo "Missed block! Check all nodes! Current height is" $MAXHEIGHT "* Node height is" $MYHEIGHT "* MemFree is" $FREEMEM "* CPU load is" $CPULOAD | mail -v -s "Missed block by forging!" $EMAIL > /dev/null 2>&1
                echo $DATE "Missed block! Current height is" $MAXHEIGHT "* Node height is" $MYHEIGHT "Send SMS, email and restart node!" >> "$LOG_FILE"
		echo $MISSED > "$DAT_FILE"
		/bin/bash $LISK_DIR/lisk.sh restart
                exit 0
        fi

	if [ $MYHEIGHT -lt $MAXHEIGHT ]; then
		echo "Incorrect height! Check node" $NODEIP "! Current height is" $MAXHEIGHT "* MemFree is" $FREEMEM "* CPU load is" $CPULOAD | mail -v -s "Incorrect height of blockchain!" $EMAIL > /dev/null 2>&1
		echo $DATE "Incorrect height! Send email! Current height is" $MAXHEIGHT "* Node height is" $MYHEIGHT "* MemFree is" $FREEMEM "* CPU load is" $CPULOAD >> "$LOG_FILE"
		exit 0
	fi

	echo $DATE "It's OK! Current height is" $MAXHEIGHT "* MemFree is" $FREEMEM "* CPU load is" $CPULOAD >> "$LOG_FILE"

else echo $DATE "Can't get info about delegate! Current height is" $MAXHEIGHT "* MemFree is" $FREEMEM "* CPU load is" $CPULOAD >> "$LOG_FILE"
fi
}

# crontab and tail logs
autostart_cron() {
  local cmd="crontab"
  command -v "$cmd" &> /dev/null
  if [ $? -eq 1 ]; then
    echo "Failed to execute crontab."
    return 1
  fi
  crontab=$($cmd -l 2> /dev/null | sed '/checker\.sh execute/d' 2> /dev/null)
  crontab=$(cat <<-EOF
	$crontab
	* * * * * $(command -v "bash") $(pwd)/checker.sh execute
	EOF
  )
  printf "$crontab\n" | $cmd - 2> /dev/null
  if [ $? -eq 0 ]; then
    echo "Crontab updated successfully."
    return 0
  else
    echo "Failed to update crontab."
    return 1
  fi
}

tail_logs() {
  if [ -f "$LOG_FILE" ]; then
    tail -f "$LOG_FILE"
  fi
}

install_ssmtp() {
  if [ $(command -v "ssmtp") ]; then
    echo "Existing ssmtp installation found."
    echo ""
  else
    echo "Installing ssmtp..."
    echo ""
    apt-get -y install ssmtp > /dev/null
    if [ $? != 0 ]; then
      echo "Failed to install ssmtp."
      exit 0
    else
      echo "Ssmtp installed successfully."
    fi
  fi
}

tune_ssmtp() {
 read -p "Enter your system user name who start lisk client(example: lisk): " user
 read -p "Enter your login name(example: lisk.grumlin): " login
 read -p "Enter your password in smtp(mail): " pass
 read -p "Enter your mail hoster(example: gmail.com): " mail
 read -p "Enter your smtp server(example: smtp.gmail.com:465): " smtp
 echo $user:$login\@$mail:$smtp > /etc/ssmtp/revaliases
 echo "mailhub="$smtp > /etc/ssmtp/ssmtp.conf
 echo "rewriteDomain="$mail >> /etc/ssmtp/ssmtp.conf
 echo "hostname="$mail >> /etc/ssmtp/ssmtp.conf
 echo "UseTLS=YES" >> /etc/ssmtp/ssmtp.conf
 echo "AuthUser="$login >> /etc/ssmtp/ssmtp.conf
 echo "AuthPass="$pass >> /etc/ssmtp/ssmtp.conf
 echo "FromLineOverride=YES" >> /etc/ssmtp/ssmtp.conf
 echo " *** If you need to change setting, edit /etc/ssmtp files or just start install else. ***"
}

case $1 in
"execute")
  exec_check
  ;;
"autostart")
  autostart_cron
  ;;
"installsmtp")
  install_ssmtp
  ;;
"tunesmtp")
  tune_ssmtp
  ;;
"logs")
  tail_logs
  ;;
*)
  echo "Error: Unrecognized command."
  echo ""
  echo "Available commands are: autostart installssmtp logs"
  ;;
esac