I have downloaded the ES tar file to install. How do i configure as init service to start and stop ES as a service.
Depends on your operating system....
Much easier to use something like a Centos RPM, it builds a systemd unit file. To create your own, see https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/system_administrators_guide/sect-managing_services_with_systemd-unit_files
We offer DEB and RPM packages with inbuilt service scripts, you would be best off using them.
If i use the tar file to install ES and if i cannot use systemd .... is there any way to run ES as a service ?