Reference 4.3 Examine Installation History
The automatic software update mechanism in OS X makes it incredibly easy for the average user to maintain an up-to-date system—so much so that the user often isn’t even aware of how many updates or installations have been applied. Yet from a support perspective, it’s important to know exactly which installations have taken place.
As you may have seen, the update screen in the Mac App Store shows recently installed updates. However, this list of updates doesn’t show the complete history of all installations, but only recent installations from the Mac App Store and only for the currently logged-in user account.
Fortunately, the System Information application features a complete installation history report. To view this history, open /Applications/Utilities/System Information, and then select the Installations item in the left column. This interface shows all software installed via the Mac App Store or the Installer application, including both new and update installations from either Apple or third parties. You can see the name, version, acquisition source, and date installed.