bash update file

#! /bin/sh
file=xyz.cfg
addr=$1
port=$2
username=$3
sed -i 's/address=.*/address='$addr'/' $file
sed -i 's/port=.*/port='$port'/' $file
sed -i 's/username=.*/username='$username'/' $file

https://stackoverflow.com/questions/14643531/changing-contents-of-a-file-through-shell-script/28559815