place var1,var2,.... inside common file tempale.xml which u need to add values automatically, eg :- config file with 2 variables, user_name=VAR1 and path=VAR2
inside php file,
$username=udara; $path=/var/www/mobsync; $create=cat tempale.xml | sed -e "s/VAR1/.$username./g" | sed -e "s/VAR2 /.$path./g" > template_new.xml; exec($create);