Crontab is a time-based job scheduler in Unix-like computer operating systems to schedule jobs
Here is how to make a Script start at boot time
Step 1: Write your script you want to run at startup and
chmod +x it to make sure it’s executable
Step 2: Run crontab command to open crondtab and edit cronjobs:
$ crontab -e
Step 3:You need to use special string called @reboot. It will run once, at startup after reboot command.
Start crond automatically at boot time