Samuel Chan onlyphantom

Specific for Linux/Ubuntu

These are what works for an out-of-the-box Ubuntu 25.04 setup running an empty-config Ghostty. Included are my most-used keyboard shortcuts and not an exhaustive list.

For a non-Ubuntu specific setup, @hensg maintains a more complete list on this Gist.

Tab Management

Action	Keyboard Shortcuts
New Tab	Ctrl + Shift + t

QuerySet API reference (stock portfolio example)

An in-depth guide to Django QuerySet (Django 3.0, updated June 2020).

When QuerySets are evaluated

Internally, a QuerySet can be constructed, filtered, sliced, and generally passed around without actually hitting the database. No database activity actually occurs until you do something to evaluate the queryset. Examples of that "something" that cause a QuerySet to evaluate:

Iteration: QuerySet executes its database query the first time you iterate over it
```
for q in Quote.objects.all():
    print(q.symbol)
```

Demystifying Docker Volumes for Mac and PC Users

Docker runs on a Linux kernel

Docker can be confusing to PC and Windows users because many tutorials on that topic assume you're using a Linux machine.

As a Linux user, you learn that Volumes are stored in a part of the host filesystem managed by Docker, and that is /var/lib/docker/volumes. When you're running Docker on a Windows or Mac OS machine, you will read the same documentation and instructions but feel frustrated as that path don't exist on your system. This simple note is my answer to that.

When you use Docker on a Windows PC, you're typically doing one of these two things:

Run Linux containers in a full Linux VM (what Docker typically does today)

	# read the full article: https://sectors.app/bulletin/deepseek

	Okay, the user is asking how many prime numbers exist between 7800 and 7920. Let me think through the steps needed to solve this.

	First, I need to list all numbers in that range and check each for primality. But doing this manually would take too long. Maybe there's a smarter way. Primes are numbers greater than 1 that have no divisors other than 1 and themselves. So for each number in the range, I need to check if it's divisible by any prime number up to its square root.

	Wait, the range is from 7800 to 7920. Let me note that the square root of 7920 is around 89, so I need to check divisibility by primes up to 89. The primes up to 89 are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89. That's a lot, but manageable.

	But maybe I can optimize. For even numbers, they are divisible by 2, so I can skip all even numbers except 2. Since the range starts at 7800, which is even, all even numbers can be excluded


	import time
	import numpy as np

	def timeit():
	"""
	a utility decoration to time running time
	"""
	def decorator(func):
	def wrapper(args, *kwargs):

	# [Created by task 2.5.1 3/9/2022 15:39:38]
	# Taskwarrior program configuration file.
	# For more documentation, see http://taskwarrior.org or try 'man task', 'man task-color',
	# 'man task-sync' or 'man taskrc'

	# Here is an example of entries that use the default, override and blank values
	# variable=foo -- By specifying a value, this overrides the default
	# variable= -- By specifying no value, this means no default
	# #variable=foo -- By commenting out the line, or deleting it, this uses the default

	INDUSTRIES = (
	('' , _('Select Industry / Sector')),
	('accounting', _('Accounting')),
	('airlines', _('Airlines/Aviation')),
	('alternative_medicine', _('Alternative Medicine')),
	('analytics_data', _('Analytics / Data Science')),
	('animation', _('Animation')),
	('apparel', _('Apparel/Fashion')),
	('architecture', _('Architecture/Planning')),
	('arts', _('Arts/Crafts')),

	1. Ayu Nur Indahsari
	2. Fatia Bani Ulfah
	3. Gede Ocha Dipa Ananda
	4. Henrico Aldy Ferdian
	5. Stane Aurelius Ronotana
	6. Vincentius Christopher Calvin

	# for username:
	# Username may only contain alphanumeric characters or single hyphens, and cannot begin or end with a hyphen
	# for repo url:
	# any valid alphanumeric including underscores

	import re
	def validate_repo_url(value):
	reg = re.compile('^([a-zA-Z\d]{1}[-a-zA-Z\d]+)(/){1}([\-\w]+)$')

	sqlConnString <- "Driver=SQL Server;Server=SETHMOTTDSVM;Database=RDB;Uid=ruser;Pwd=ruser"
	# read in chunks of 100000
	sqlRowsPerRead <- 100000
	sqlTable <- "NYCTaxiBig"

	ccColInfo <- list(
	tpep_pickup_datetime = list(type = "character"),
	tpep_dropoff_datetime = list(type = "character"),
	passenger_count = list(type = "integer"),
	trip_distance = list(type = "numeric"),