Reminders on handy tech tips & reminders

Reminders for Microsoft Windows

Tue, 01 Sep 2026 11:51:46 +0100

Various handy tips and shortcuts

Shift-F10 : (during OOBE) open a Command Window
Control-Shift-F3 : (during OOBE ) logs you in as Administrator
Control-Shift-Win-B : Windows desktop manager/display reset

Useful command-window commands:

Reboot now : C:> SHUTDOWN /R /T 0
see who is logged on : C:> QUERY USER
see if PC is joined to a domain : C:> SET USER
see when last rebooted : C:> NET STATISTICS WORKSTATION OR C:> SYSTEMINFO (also shows lots of other useful info, such as which Hotfixes have been installed)
recursive search for a file : C:> DIR /S *REALTEK* ( /S meaning “scan subfolders too” )
Laptop battery health report: C:>POWERCFG /BatteryReport - will write the report to a file and show you the filename

Useful Powershell/‘Terminal’ commands :

Linux apt Package Manager

Sun, 30 Aug 2026 10:11:27 +0100

Since I mainly use Debian-based Linux flavours, I have had to get used to the apt package manager which Debian uses. I find it a bit unintuitive to use, as there seem to be several different programs to do basic things.

Note: many of the apt commands shown below need to run as root, so you should prefix each command with ‘sudo’ if running as a normal user.

# apt update - this downloads package information from the internet on which packages/versions are available. N.B. it does not actually update any packages, it just updates the package manager’s catalogue/cache/list of what updates are available.

Mac keyboard shortcuts

Fri, 28 Aug 2026 08:46:27 +0100

Handy reminders of some of the many useful things you can do with keyboard combinations on a Mac.

Note: if you’re using a PC keyboard, ‘Option’ is the Alt key , and ‘Command’ is the Windows key

Key combination	what it does
Command-Shift-4	Take a screen capture (selected area)
Command-Shift-3	Take a screen capture (whole screen, saved straight to your desktop)
Option-#	print the £ sign (if you have a U.S keyboard)
Ctrl-Command-spacebar	to type an emoji
Command-F1	display on external monitor

AT POWER-ON :	(i.e. hold the keys down when powering on)
Option (Alt)	Boot menu - e.g to boot from a USB stick
D	Diagnostics mode
Command-R	Recovery mode
Option-Command-R	?Internet Recovery mode - may offer more recovery options

Reset combinations :
SMC Reset	Shutdown your Mac, then hold `Left-hand-Shift + Control + Option (Alt)` , then press Power button for 10 sec . ( can be useful for power/charging issues, fans, hot PC, or webcams not working)
NVRAM Reset	hold down `Option+Command+P+R` for about 20 sec when powering on. Release after 2nd startup sound. ( only for older/Intel Macs, not for M1 and later. Can resolve problems with audio, screen resolution, clock, slow startup etc)

Dell Latitude blink codes

Wed, 26 Aug 2026 08:52:44 +0100

When a Dell laptop encounters a hardware problem, it may blink its LEDs in a certain pattern, which indicates where the fault lies.

Dell Latitude 2017-2023

The battery charge LED will blink X times in amber (orange) colour, then Y times in white.

X , Y	FAULT
2 , 1	CPU
2 , 2	Motherboard BIOS/ROM error
2 , 3	No RAM detected
2 , 4	RAM failure
2 , 5	invalid RAM
2 , 6	motherboard Chipset error
2 , 7	LCD failure
2 , 8	LCD power rail failure
3 , 1	RTC/CMOS battery
3 , 2	PCI or graphics/video card
3 , 3	BIOS recovery image not found
3 , 4	BIOS recovery image invalid
3 , 5	Power rail failure
3 , 6	SBIOS flash corruption
3 , 7	ME error

Latitude 2015-2017

Same blink codes as above, but it’s the Power button LED which flashes.

Reminders for MacOS

Sun, 23 Aug 2026 12:30:22 +0100

Section ONE

Create a USB stick to install MacOS

Find a download link for the version of MacOS you want ( usually a large 7GB file named something like ‘Install macOS Sequioa’ )
Use the MacOS Disk Utility to erase a 16GB USB stick : choose format type ‘MacOS Extended format’, and give it a name like ‘sequoiastick’ or similar
In a Terminal Window , type

sudo /Applications/Install\ macOS\.Sequioa.App/Contents/Resources/createinstallmedia --volume /Volumes/sequoiastick

MacOS versions

from Catalina back to Mountain Lion were known as ‘OS X’ ; Lion back to Leopard were ‘Mac OS X’

Version	Name	Date
16	T	June 2025
15	Sequoia	2024
14	Sonoma	2023
13	Ventura	2022
12	Monterey	2021
11	BigSur	2020
10.15	Catalina	2019
10.14	Mojave	2018
10.13	High Sierra	2017
10.12	Sierra	2016
10.11	El Capitan	2015
10.10	Yosemite	2014
10.9	Mavericks	2013
10.8	Mountain Lion	2012
10.7	Lion	2010
10.6	Snow Leopard	2008
10.x	Leopard

various Linux reminders

Sun, 16 Aug 2026 09:31:46 +0100

Reminders on how to do various things in Linux which I always have difficulty remembering. Many are for Debian Linux, since I mainly use Debian-based systems: Raspberry Pi , Ubuntu, Zorin OS and small ARM/embedded systems such as Seagate Dockstar.

Section One

ps -ef |grep ntp

find . -name "pnec*" -mtime +50 | xargs ls -l ( takes a couple of minutes)