Run script at boot as service

This is achieved using the init run-level based rc scripts. Basically the command "service" used to start and stop system services. for example "service <your script> start".

  # update boot / reboot files   
  sudo cp <your script> /etc/init.d/ # <your script> your script file with the path   
  # do it as soon as the device is going down,   
  # both for shutdown and reboot   
  sudo chmod u+x <your script>   
  sudo update-rc.d /etc/init.d/<your script> defaults   

The <your script> is : 

   #! /bin/sh   
   ### BEGIN INIT INFO   
   # Provides:   <your script name>   
   # Required-Start: $all   
   # Required-Stop:    
   # Default-Start:  2 3 4 5   
   # Default-Stop:  0 1 6   
   # Short-Description: Manage my cool stuff   
   ### END INIT INFO   
   PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/opt/bin   
   . /lib/init/vars.sh   
   . /lib/lsb/init-functions   
   # If you need to source some other scripts, do it here   
   case "$1" in   
   start)   
    log_begin_msg "Starting my super cool service"   
   # do something   
    log_end_msg $?   
    exit 0   
    ;;   
   stop)   
    log_begin_msg "Stopping the coolest service ever unfortunately"   
    # do something to kill the service or cleanup or nothing   
    log_end_msg $?   
    exit 0   
    ;;   
   *)   
    echo "Usage: /etc/init.d/<your script> {start|stop}"   
    exit 1   
    ;;   
   esac   

Then replace # do something with the content of your original script. for example : 
 

 sudo service hostapd stop  
 sudo service udhcpd stop  
 sudo service hostapd start  
 sudo service udhcpd start