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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.

No worries. You do need to copy it to the /etc/init.d as you mentioned. This will only tell the system how it can start/stop/restart the arcgisserver service. However you still need to tell it you want it to start at boot.

All the major distros now use something called systemD which handles starting up the system, so you have to do two other small things, listed below, to get it to start on boot.

To interact with system you mainly use the systemctl command to tell it what you want to do .

 The following will tell systemD to start the arcgisserver service.

systemctl start arcgisserver

This next command will tell systemD to start it EACH time it boots up.

	# 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;
	}

	#!/usr/bin/env python

	import math
	import matplotlib.pyplot as plt
	import torch
	import torch.nn as nn

	from sklearn.datasets import make_moons
	from torch import Tensor
	from tqdm import tqdm