Writing startup scripts using init script method

Creating systemd services has been goto startup scripts for the modern times, but there are times this method fails due to some reason, recently I wanted to write a startup script for my spot ec2 instance, So that whenever the machine reboots, the critical services like game-server, bot-server etc. should start with it.

But my game-server and bot-server relied on some third party tools, which took some time to load after system reboot, So I wasn't able to start those necessary services using systemd.

So, I tried init script method and fortunately this worked.

Here's step by step guide to make your own startup scripts with init script method.

Instructions

Create a new script file, let's call it myscript, in the /etc/init.d/ directory:
```
    sudo nano /etc/init.d/myscript
```

Add the following code to the myscript file:

     #!/bin/bash
     # chkconfig: 2345 99 01
     ### BEGIN INIT INFO
     # Provides:          myscript
     # Required-Start:    $remote_fs $syslog
     # Required-Stop:     $remote_fs $syslog
     # Default-Start:     2 3 4 5
     # Default-Stop:      0 1 6
     # Short-Description: Start My Script at boot time
     # Description:       Enable service provided by My Script.
     ### END INIT INFO
     # chkconfig: 2345 20 80
     # description: My Script

     # Source function library.
     . /etc/init.d/functions

     start() {
         echo "Starting My Script"
         su - ec2-user -c "/home/ec2-user/auto_start.sh"
     }

     stop() {
         echo "Stopping My Script"
         # Add any necessary stop actions here
     }

     case "$1" in
         start)
             start
             ;;
         stop)
             stop
             ;;
         restart)
             stop
             sleep 2
             start
             ;;
         *)
             echo "Usage: $0 {start|stop|restart}"
             exit 1
     esac

here auto_start.sh was the script, I wanted to run after system reboot.

Save the file and make it executable:
```
 sudo chmod +x /etc/init.d/myscript
```
Register the init script with the system:
```
sudo chkconfig --add myscript
```
Configure the init script to start automatically at system startup:
```
sudo chkconfig myscript on
```

Done :)

Now the content of auto_start.sh will run whenever your system reboots, even if the processes in the script are dependent on some third party tools to load first.

I hope you found this helpful. Feedback are welcome. Thank you!!