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Install WordPress v5.3.2 and self-host it over https using Nginx.

Prerequisites

MariaDB 10.4.13 (Reference How To Install MariaDB 10.4 on Ubuntu 18.04 / Ubuntu 16.04)
php 7.4.3 (Reference How To Install PHP 7.4 on Ubuntu 20.04/18.04/16.04)

php installs Apache2 too. Disable it and remove it if you want to use Nginx.

Common Useful MySQL / MariaDB Commands

User Creation, Manipulation, Deletion

Show all users in the mysql database:

MariaDB [(none)]> select * from mysql.user;
Delete a null user:

pip was broken after I installed pip3.8 and removed some other python links.

To fix pip:

python2 -m pip install --user --upgrade pip

python3 -m pip install --user --upgrade pip

Python: load a script in Python shell

This is usually for some quick testing.

python -i myscript.py

Then you can reference functions and variables in the script directly.
While you are already in a Python shell:

https://en.wikipedia.org/wiki/ASCII#Printable_characters

Codes 20 to 7E, known as the printable characters, represent letters, digits, punctuation marks, and a few miscellaneous symbols. There are 95 printable characters in total.

Code 20, the "space" character, denotes the space between words, as produced by the space bar of a keyboard. Since the space character is considered an invisible graphic (rather than a control character) it is listed in the table below instead of in the previous section.

Code 7F corresponds to the non-printable "delete" (DEL) control character and is therefore omitted from this chart; it is covered in the previous section's chart. Earlier versions of ASCII used the up arrow instead of the caret (5E) and the left arrow instead of the underscore (5F).

Javascript:

Notes from Practical Git for Everyday Professional Use on egghed.io.

git init

Initialize the current local directoy as a git repository locally.

git init --bare will make the local directory a bare repository which will act as a remote respository.

git clone `<link>`

Clone a remote repository locally. New directory will be created.

NodeJS

// base64 encoding a file
const base64EncodedString = fs.readFileSync(imageFileName).toString('base64');
// saving a base64 encoded image to a file
fs.writeFileSync(imageFileName, Buffer.from(base64EncodedString, 'base64'))

Python

	Set environment variables for proxies.

	Windows:
	set http_proxy=http://xxx.xxx.xxx.xxx:80
	set https_proxy=http://xxx.xxx.xxx.xxx:80

	Bash:
	http_proxy=http://xxx.xxx.xxx.xxx:80
	https_proxy=http://xxx.xxx.xxx.xxx:80

	#!/usr/bin/env python3

	import os
	import sys
	import subprocess
	import tempfile

	f = 'mycerts.pem' if len(sys.argv) == 1 else sys.argv[1]

	if os.path.exists(f) and os.path.isfile(f):

	#!/usr/bin/env python3
	'''
	You have notes in 3 denominations: two, five and ten.
	Write a function `change` which takes in one argument which is the money amount,
	and return the combination of the 3 notes using minimum number of notes
	that adds up to the given amount.
	Return None if it is not able to add up to the amount.
	Assume you have infinite supply of notes in all 3 denominations.
	Examples:
	1: the function should return None