Since Nginx is on port 80, you should tell nginx to forward all php requests to apache on port 8081. For that add the domain virtual host entry as below :
=============================
server {
listen 80;
# listen *:80;
server_name arun.in;
location / {
root /home/arun/public_html/;
index index.html index.htm;
}
location ~ \.php$ {
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $remote_addr;
proxy_set_header Host $host;
proxy_pass http://127.0.0.1:8081;
}
location ~ /\.ht {
deny all;
}
}
=============================
Once this is done, add the virtual host entry in apache.
==============================
<VirtualHost 127.0.0.1:8081>
ServerAdmin arun@ffff.com
DocumentRoot "/home/arun/public_html"
ServerName arun.in
ServerAlias www.arun.in
ErrorLog "logs/arun.in/error_log"
CustomLog "logs/arun.in/access_log" common
</VirtualHost>
If you have not yet installed php, folow the link here.
Restart Apache and Nginx.