WordPress
Getting started with WordPress by WordPress: https://codex.wordpress.org/Getting_Started_with_WordPress
Codex, WordPress manual: https://codex.wordpress.org/
Great starter stuff: https://www.wpbeginner.com/
Developer’s guide to WordPress, by WordPress: https://developer.wordpress.org/
Plugin Developer Handbook: https://developer.wordpress.org/plugins/
Get involved with WordPress.org! https://make.wordpress.org/
Kinsta has an amazing knowledge base: https://kinsta.com/knowledgebase/
This is sweet, full list of WP hooks: https://adambrown.info/p/wp_hooks
Linux
Excellent source for tutorials re: all things Linux: https://linuxize.com
Python
Python Turtle Module: https://docs.python.org/3.3/library/turtle.html