sys_util.sh

#! /bin/sh

get_meminfo_value() {
	echo $(echo "$1" | grep -w "$2" | tr -s " " | cut -d ' ' -f 2)
}

mem_util() {
	local meminfo="$(cat /proc/meminfo)"
	local total=$(get_meminfo_value "$meminfo" MemTotal)
	local free=$(get_meminfo_value "$meminfo" MemFree)
	local buffers=$(get_meminfo_value "$meminfo" Buffers)
	local cached=$(get_meminfo_value "$meminfo" Cached)

	local used=$((total - free - buffers - cached))
	local used_percent=$((used * 100 / total))
	
	echo $used_percent
}

cpu_util() {
	cpu1=$(grep '^cpu ' < /proc/stat)
	idle1=$(echo $cpu1 | awk '{print $5}')
	total1=$(echo $cpu1 | awk '{print $2+$3+$4+$5+$6+$7+$8+$9+$10}')

	sleep 1

	cpu2=$(grep '^cpu ' < /proc/stat)
	idle2=$(echo $cpu2 | awk '{print $5}')
	total2=$(echo $cpu2 | awk '{print $2+$3+$4+$5+$6+$7+$8+$9+$10}')

	idle_delta=$((idle2 - idle1))
	total_delta=$((total2 - total1))

	cpu_util=$((100 * (total_delta - idle_delta) / total_delta))

	echo $cpu_util
}

BOT_TOKEN="<telegram-bot-token>"
CHAT_ID="<telegram-chat-id>"

SAMPLE_RATE=5
CPU_THRESHOLD=80
MEM_THRESHOLD=80

 send_telegram_msg() {
	curl -s -X POST "https://api.telegram.org/bot$BOT_TOKEN/sendMessage" \
		-d chat_id="$CHAT_ID" \
		-d text="$1" \
		-d parse_mode="HTML"
}

check_sys_util() {
	mem_util=$(mem_util)
	if [[ mem_util -gt $MEM_THRESHOLD ]]; then
		send_telegram_msg "High Memory Usage Alert: ${mem_util}%"
	fi
	
	cpu_util=$(cpu_util)
	if [[ cpu_util -gt $CPU_THRESHOLD ]]; then
		send_telegram_msg "High CPU Usage Alert: ${cpu_util}%"
	fi
}

while true; do
	check_sys_util
	sleep $SAMPLE_RATE
done