use variable in string shell script code example

Example 1: sh declare variable

#!/bin/sh
MY_MESSAGE="Hello World"
echo $MY_MESSAGE

Example 2: bash use variable in string

domain='http://www.whitehouse.gov'
path='/some/path'
base_url="$domain$path"

Example 3: bash variable in string

${!var}	#Just use to use reference value inside another variable ;)