Cleaning Up Windows Without Interaction

To reduce the size of some of my virtual machines, I often run the Windows cleanup tool to get rid of update artifacts and temporary files. While the cleanmgr command has some undocumented options such as /setup, /autoclean and /verylowdisk, I could not achive what I wanted with any combination of these: I wanted to have one command that simply cleans _everything_ without interaction. TL;DR: Put this in a batch file:
@echo off
set rootkey=HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches
for /f "tokens=*" %%K in ('reg query %rootkey%') do >NUL REG add "%%K" /v StateFlags0000 /t REG_DWORD /d 2 /f
cleanmgr /sagerun:0

Essentially, this script manually creates the registry keys that would be created by a call to cleanmgr /sageset:0 and checking all the boxes. It then runs cleanmgr /sagerun:0 which non-interactively calls cleanmgr performing every cleanup task available. Remember to run this as an administrator to remove Windows update artifacts. Would you like to have that as PowerShell?

How to farm the Win10 key from a Win7 Upgrade in VirtualBox

Scenario. You have a Windows 7 key and want to farm a Windows 10 key from it, using the automatic upgrade. Of course, you want to do this in a VirtualBox[1]. The first thing you do is, set up a VM with at least 30GB of harddrive. Let's assume that this VM is called Nekarat. This is an outdated pop culture reference, google it. In the host system (not the VM), go to your happy place (i.e. cmd.exe) and do this:
cd c:\Program Files\Oracle\VirtualBox

Windows Registry Editor Version 5.00