Rename File With Period Dot . In Mac X
Open Terminal in Mac X Utilities folder
Type: cd /path/to/current/file-to-rename (you can drag and drop the path too into Terminal window)
Type: mv "file-to-rename" .file-to-rename
The file will be renamed with a period or dot in front of it. Keep in mind the file will by hidden now. You will need to show hidden files to reveal the file again.