They’re hidden away and never promoted at WWDC, but vitally important to every Mac user. Could you imagine not having Disk Utility, for example?
If you’re familiar with the macOS log and have problems with an iOS device, you can easily access its log to help in diagnosis.
As macOS gets more complex, diagnostic and control tools provided by Apple have become less accessible. This makes macOS harder to diagnose and support.
Enjoy being a computer owner-user-maintainer while you can: those days are NUMbered.
How to run individual components from sysdiagnose.
Looking in greater detail at what you can get from running sysdiagnose.
ps and top are far superior tools for looking at processes than Activity Monitor.
When you have tried everything else, this shell command will throw the book at your problem, running all the diagnostics it can.