When software updates for OS X and apps you have purchased in the App Store become available, by default you will see a message in Notification Center, which you can click to launch the App Store and apply the updates. In the past Apple has offered options to download updates in the background, and install important security updates and app updates, but in Yosemite has included new options that encompass all software updates.
If you go to the App Store system preferences in Yosemite, you will see a new option you can check to “Install OS X Updates.” As with the setting for managing App updates, this is made unavailable until you check the option to download new software updates in the background. When enabled, however, as with the management of App Store updates, this will ensure your operating system software is kept fully up to date.
Overall, the options in the App Store system preferences are the following:
- Automatically check for updates — This will only check for software updates and notify you about them, as opposed to doing any automatic downloads and installations.
- Download newly available updates in the background — This will likewise not install any updates, but will make them quicker to install when you are ready, by having them stored on your system instead of needing to be downloaded on-demand from the App Store.
- Install app updates — This will automatically update any App Store applications that you have installed, to ensure they are at the latest versions.
- Install OS X updates — This is the new feature, which will install any OS X updates available from Apple, automatically restarting your system for them to take effect.
- Install system data files and security updates — This will install any critical security updates automatically, to ensure known vulnerabilities and exploits for them are patched.
You might wonder whether or not it is wise to enable any of these features. In most cases, I would recommend against automatic update processes, especially if you use your Mac every day where you will see notifications for any available updates and be able to manage them at your convenience.
The only features in this system preference that I would suggest enabling for your main Mac are the automatic check for updates, and perhaps the option to download newly available updates in the background; however, the others are good options to have and are perhaps best for systems that you might not use all the time, such as system you are using as a local file server, or systems that are part of a computer lab or workgroup. In these instances, you can use these features to keep them as up to date as possible.