Backup

There are many questions about how to
home-manager.backupCommand to override the default backup behavior. If you dont care about backups, you can also set home.file."file.foo".force = true; to force overwriting of existing file.

How to symlink some files without copying their content in the store ?

Use home.file."file.foo".source = config.lib.file.mkOutOfStoreSymlink ./path/to/file/to/link;