Procedure To Run An Application As Daemon In Linux

DESCRIPTION:

• I wrote a simple server program in C. It monitor my client application.
• Client application need to send acknowledge to server continuously with out any help from user.
• So i making my client application runs in background and it should start at boot time.

PROCEDURE:

• My client application name is client_ack. Copy this file to bin directory

         sudo cp client_ack /bin/client_ack

• Go to the /etc/init.d/ directory and create a file and 

         cd /etc/init.d

         sudo vi client_d

• Write the following script into file

         #!/bin/sh

         ### BEGIN INIT INFO

         # Provides:          client_d

         # Required-Start:    $network $remote_fs $syslog

         # Required-Stop:     $network $remote_fs $syslog

         # Should-Start:      network-manager

         # Should-Stop:       network-manager

         # X-Start-Before:    $x-display-manager gdm kdm xdm wdm 

                              ldm sdm nodm

         # X-Interactive:     true

         # Default-Start:     2 3 4 5

         # Default-Stop:      0 1 6

         # Short-Description: server client application

         ### END INIT INFO

         USAGE="usage: $0 {start|stop}";    

         usage() {

             echo $USAGE >&2

         }     

    

         ss_start() {

             cd /bin

             rm -r nohup.out

             exec nohup ./client_ack &

             sleep 3

             echo ""

         }

     

         ss_stop() {

             killall -9 client_ack

         }

         case $1 in

             start) ss_start ;;

             stop) ss_stop ;;

             *) usage

             exit 1

             ;;

         esac

• Give executable permission to client_d file

         chmod +x client_d

• Create symbolic link for start up using following command

         sudo update-rc.d client_d defaults

• Restart the PC
• You can check the client_d process running by using following command

         ps aux | grep client_d

• You can Stop and Start the client_d manually by using following commands

        TO START : sudo service client_d start

        TO STOP  : sudo service client_d stop

• Now my server getting acknowledgement message from client without any help from user and its start at boot time.