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Common Terminal Commands

Key Commands & Navigation

Before we look at some common commands, I just want to note a few keyboard commands that are very helpful:

Up Arrow: Will show your last command
Down Arrow: Will show your next command
Tab: Will auto-complete your command
Ctrl + L: Will clear the screen

How to mount a qcow2 disk image

This is a quick guide to mounting a qcow2 disk images on your host server. This is useful to reset passwords, edit files, or recover something without the virtual machine running.

Step 1 - Enable NBD on the Host

modprobe nbd max_part=8

File Magic Numbers

Magic numbers are the first bits of a file which uniquely identify the type of file. This makes programming easier because complicated file structures need not be searched in order to identify the file type.

For example, a jpeg file starts with ffd8 ffe0 0010 4a46 4946 0001 0101 0047 ......JFIF.....G ffd8 shows that it's a JPEG file, and ffe0 identify a JFIF type structure. There is an ascii encoding of "JFIF" which comes after a length code, but that is not necessary in order to identify the file. The first 4 bytes do that uniquely.

This gives an ongoing list of file-type magic numbers.

Image Files

The biggest issue with Herd Pro is that you cannot use Reverb out of the box with a site that has SSL enabled. Here is the workaround for it all to play nicely together.

First you will need to create two sites. The two I have here are as follows:

reverb-ssl - This is a new Laravel 11 project using Breeze for the ease of Inertia. This also follows the setup for Reverb line by line.
wss-reverb-ssl - This is an empty directory, we are going to use this only for editing a Nginx config and setting up a proxy to the reverb service.

Of note is that I'm using Herd Pro as well, so all additional services are being used directly though Herd Pro itself.

	# https://docs.microsoft.com/en-us/graph/powershell/installation
	# https://docs.microsoft.com/en-us/graph/powershell/get-started
	# https://developer.microsoft.com/en-us/graph/graph-explorer
	# https://tech.nicolonsky.ch/exploring-the-new-microsoft-graph-powershell-modules/

	Connect-MgGraph -Scopes "User.Read.All", "GroupMember.Read.All", "Group.Read.All", "Directory.Read.All"
	$GROUP_NAME = 'Workspace'

	$group = Get-MgGroup -Filter "DisplayName eq '$GROUP_NAME'"

	// ts 3.6x
	function debounce<T extends Function>(cb: T, wait = 20) {
	let h = 0;
	let callable = (...args: any) => {
	clearTimeout(h);
	h = setTimeout(() => cb(...args), wait);
	};
	return <T>(<any>callable);
	}

	# Editing a virtual machine file

	# This PowerShell code takes an unregistered VMCX file
	# It change the VM Name, disables Dynamic Memory, and sets the memory to 2GB
	# It then saves the changed virtual machine configuration to a new path

	# Parameters that will be changed
	$VMConfigurationToEdit = "D:\VMs\Virtual Machines\3F99446F-1D9A-4010-8C8B-4E554E845181.vmcx"
	$pathToSaveNewConfigTo = "D:\"
	$newVMName= "NewVMName"

	#!/bin/sh

	PHP_MSSQL_DRIVERS=Ubuntu18-7.3
	PHP_MSSQL_RELEASE=5.6.1

	# Download and extract phpmysql drivers
	sudo wget "https://github.com/Microsoft/msphpsql/releases/download/v${PHP_MSSQL_RELEASE}/${PHP_MSSQL_DRIVERS}.tar" -O - \| tar -x

	# Change Directory
	cd $PHP_MSSQL_DRIVERS

	Alpine.directive('typed', (el, { expression, modifiers }, { evaluateLater, effect, cleanup }) => {
	const getStrings = evaluateLater(expression);

	const modifierValue = (key, fallback) => {
	if (-1 === modifiers.indexOf(key)) {
	return fallback;
	}

	const value = modifiers[modifiers.indexOf(key) + 1];

	using Unity.Entities;
	using UnityEngine;

	namespace TMG.ECS_Transforms
	{
	[GenerateAuthoringComponent]
	public class BattleStageManagedData : IComponentData
	{
	public Transform TrackFollower;
	}