I was trying to replace all variables based on some type of identifier (i.e. a variable name encapsulated with ${}) similar to this Azure DevOps task. You would have to specify the file, but would prevent you from having to run this command once for each and every variable you want to insert. I’m guessing CircleCI doesn’t have this feature?
https://marketplace.visualstudio.com/items?itemName=qetza.replacetokens