-------------- Server side Work ---------------------

mkdir /var/repo

mkdir repo_name.git

git init --bare

vim post-receive

#!/bin/sh
git --work-tree=/var/www/html --git-dir=/var/repo/repo_name.git checkout -f

save file post-receive and make it executable chmod +x post-receive

----------------- client side Work ---------------------

git remote add live ssh://user@address/var/repo/repo_name.git git push live master

But Before all of these configuration set ssh-keygen features https://github.com/gitachyut/ssh-key-setup

This is not step by step code deploy way it's one time code deploy.

• using github and git
• using the github webhook (https://github.com/gitachyut/best-code-deploy/settings/hooks/new) feature (link your bellow script location eg; http://example.com/script.php )
• script.php

<?php
	$Local_Root = "/home/site/web/xyz.com/public_html";
	$App_name = "app";
	$Local_repo = "{$Local_Root}/{$App_name}";
	$Git_repo = "https://github.com/gitachyut/abc.git";
	$Git_repo_name = "abc";
	if(file_exists($Local_repo)){
		shell_exec("rm -rf {$Local_repo} "); 
	}
	echo shell_exec(" cd {$Local_Root} && git clone {$Git_repo} && mv {$Git_repo_name} {$App_name}  && git checkout master ");
	die("done");
?>

create a config file in ~/.ssh dir

host host_url/ip  
 HostName host_url/ip  
 IdentityFile ~/.ssh/your_private_key  
 User user_name  

git remote add live ssh://user_name@host_url_ip/directory/full/path/repo.git