How can I pass variables to a file printed from outside a bash script?

Assuming I have a variable v="c d e f g" and a file with the content: line1 $v line3 How can I make a bash script print this file with the content of the variable in line 2 as if I was using a here-document like this: #!/bin/bash v="c d e f g" cat << EOF line1 $v line3 EOF Output: line1 c d e f g line3