update value in bash script - bash

Question

i have stuck code. i make bash script to send Notification If file Size changed
#!/bin/bash
#File Embeded
test_file=/home/optimus/bot_test/dump.txt
msg_caption=/tmp/telegram_msg_caption.txt
#initialize
initCount=0
#checkLog
#cmd="ls /var/log/snort/* | wc -l"
cmd=$(wc -c "dump.txt" | awk '{print $1}')
#Chat ID and TOKEN Telegram
chat_id="xxxx"
token="xxx"
#Send Alert
function sendAlert
{
curl -s -F chat_id=$chat_id -F caption="$caption" -F document=#$test_file https://api.telegram.org/bot$token/sendDocument > /dev/null 2&>1
}
#Monitoring DoS Server
while true
do
#GetLastCount
echo "Start Execute"
lastCount=$cmd
echo before_last $lastCount #ex 100 #after reset 0
echo before_init $initCount #ex 0
echo "--------------------"
if(($(($lastCount)) > $initCount));
then
echo "Running Script..." #debug
echo -e "Halo Admin\nTerjadi Indikasi Penyerangan DoS!!!" > $msg_caption #set Caption / Pesan
caption=$(<$msg_caption) #set Caption
sendAlert #Panggil Fungsi
#error disini
initCount=$lastCount
lastCount=0 #reset
echo after_last $lastCount
echo after_Init $initCount
echo "==================="
rm -f $msg_caption
sleep 5 #delay Proses jika ada indikasi
fi
sleep 5 #delay proses jika tidak ada indikasi
done
when code first running, send First Notification, and if file size changed , value in code not updated
example i use dump.txt to object size changed
how to get Last Size from dump.txt after
echo "Start Execute"
conclusion every 5 second, lastCount get last size File updated

Answer 1

The problem in your code is that the cmd=$(wc -c "dump.txt" | awk '{print $1}') line executes only once.
Instead, you should use:
#....
do
#...
lastCount=$(wc -c "dump.txt" | awk '{print $1}')
#...
Or make the cmd a function or store in a string and evaluate the string. The way you wrote, it is only evaluated in the beginning of your script and you use the same value afterward.