What should I do when I add a new config parameter to config file of my package?

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http://stackoverflow.com – I am dealing with making some packages of some projects. Assume I have a config file like that in my project. name=foo mail=[email protected] After installation user edits config file with his/her information. name=user mail=[email protected] When a update comes, for the purpose of not ruin the users config file, I do not replace conf file with new ones as all packages should do. There is no problem up to this point. What if I add a new parameter to my config file? For example, name=foo mail=[email protected] age=23 If I replace config file with new one, user will lost its settings. If I (HowTos)