The restore.log file on the Update volume contains details of all macOS updates installed since 11.0.1. Here’s a quick guide to its contents and use.
softwareupdate
What’s normal for patterns of security data and macOS updates? How to recognise the pathological, which could reflect a security failure.
Some are reporting that recent MRT updates have been installed 15 times. If your Mac affected? Does it keep installing the same security data updates?
If you don’t want to leave Software Update to install updates automatically, here are the options for using softwareupdate, SilentKnight and silnite instead.
You might want an old macOS or OS X installer to build a Virtual Machine, or for an old Mac. Here’s how to get them, and old versions of Xcode.
For those who want macOS updates promptly, SilentKnight can be a help. But don’t use it to download and install an update.
What to do when SilentKnight offers you large macOS updates, or updates which you don’t want to install just yet, and other problems.
Full macOS installers come in different presentations according to how they’re obtained. Explained here are what’s in an installer app, and how a bootable installer disk works.
In macOS 11.5.1, Apple has squeezed a thimbleful of a patch into a ten-gallon can of update, more than 99% of which is overhead.
Details of how the Content Caching server handles a cache macOS security data update, and both client and server handle an App Store update.
The Eclectic Light Company 