I am a developer and I try to sell my applications the right way. What do I mean by that? If you buy one of my applications you can install and use them on as many Macs you like. You pay for the app once and then you can use it everywhere. Other developers don't like that and take action to enforce this policy. But what do customers do when you allow them to use your application everywhere? Well, they do. Especially in the case of my application Flashcards (a flash-cards application for OS X) my "liberal" policy raises a problem: Flashcards has no built in sync functionality but people would like to work with the same data everywhere. I will now explain how to enable sync in Flashcards although Flashcards has no built in sync functionality. The process I am describing can be applied to a lot of other applications as well (at your own risk of course). So let's get started.
1. Go to Dropbox.com sign up. If you already have a Dropbox account you can of course skip this step.
2. Open the Finder and go to Libary - Application Support. This folder contains a lot of folders - usually you will find a folder for each application you are using. An application typically stores user data inside its application support folder. Note: If you don't find the application folder in Application Support navigate back to the Library folder. Some applications prefer to have their folder located there.
3. In the case of Flashcards open the folder called Ebbinghaus3. The folder is called Ebbinghaus3 and not Flashcards because a few months ago Ebbinghaus was renamed to Flashcards.
4. Move the file Ebbinghaus3.sql to your Dropbox folder.
5. Open the Terminal and type in the following commands:
$ cd "Library/Application Support/Ebbinghaus3"/
$ ln -s ~/Dropbox/Ebbinghaus3.sql Ebbinghaus3.sql
6. The above command creates a link called Ebbinghaus3.sql which points to the real Ebbinghaus3.sql file which is now located in your Dropbox folder.
7. Perform step 4 and 5 on every Mac that you own.
From now on every time you hit command + s in Flashcards the data is stored in the Dropbox folder and gets synced with your other Macs.