What is best practice to handle whitespaces when letting user to edit configuration, the name=value pairs?

For instance, you let user to define the notorious path variable. How do you interpret the path = blah blah? This looks like a programming language adopted practice to ignore the white spaces and you leave them around the eq mark for readability but it might be a valid variable value with white space in the app (consider, it is a suffix). Even keys may contain whitespaces, can't they? What is the general best practice for my app? Is it treating every value separately?