Alfred Gutierrez · アル alfg

Note

I’ve written a newer optimized 2026 version of this guide with a faster setup using Zinit + Starship and improved plugin loading.

This version avoids slow shell startups and works better with modern Zsh setups.

Updated guide: https://gist.github.com/n1snt/2cccc8aa5f7b645a7628d3512c70deb6

Oh my zsh.

Risk Assessment of GitHub Copilot

0xabad1dea, July 2021

this is a rough draft and may be updated with more examples

GitHub was kind enough to grant me swift access to the Copilot test phase despite me @'ing them several hundred times about ICE. I would like to examine it not in terms of productivity, but security. How risky is it to allow an AI to write some or all of your code?

Ultimately, a human being must take responsibility for every line of code that is committed. AI should not be used for "responsibility washing." However, Copilot is a tool, and workers need their tools to be reliable. A carpenter doesn't have to

Car hacking with ScanTool ECUSim 2000

An upcoming project has me looking at car hacking at the moment. I watched a great video ( https://www.youtube.com/watch?v=nvxN5G21aBQ ) which caught me up to speed on the fundamentals. There are a few other videos out there on introductory car hacking, but they all seem to revolve around the virtual can interface provided by vcan. I decided I didn't want to test virtually because then I wouldn't know how to work with the actual connection hardware. At the same time, being a beginner, I DID NOT want to plug into my personal vehicle's ODB2 port.

I was looking for something between vcan and a real car. A little googling led me to the ScanTools ECUSim 2000: https://www.amazon.com/OBDLink-ScanTool-ECUsim-Simulator-Development/dp/B008NAH6WE

This board simulates a car. It has a ODB2 port for interfacing just like one would do with a

Introduction

This document contains some of the ffmpeg snippets I use most commonly, and typically in the context of converting research-related image data to video. It is not meant to be exhaustive.

FFmpeg cheat sheet

A list of useful commands for the FFmpeg command line tool.

Download FFmpeg: https://www.ffmpeg.org/download.html

Full documentation: https://www.ffmpeg.org/ffmpeg.html

Basic conversion

Falsehoods programmers believe about time

This is a compiled list of falsehoods programmers tend to believe about working with time.

Don't re-invent a date time library yourself. If you think you understand everything about time, you're probably doing it wrong.

Falsehoods

There are always 24 hours in a day.
February is always 28 days long.
Any 24-hour period will always begin and end in the same day (or week, or month).

	# Put this function to your .bashrc file.
	# Usage: mv oldfilename
	# If you call mv without the second parameter it will prompt you to edit the filename on command line.
	# Original mv is called when it's called with more than one argument.
	# It's useful when you want to change just a few letters in a long name.
	#
	# Also see:
	# - imv from renameutils
	# - Ctrl-W Ctrl-Y Ctrl-Y (cut last word, paste, paste)

	#!/usr/bin/env bash

	# Installs ffmpeg from source (HEAD) with libaom and libx265, as well as a few
	# other common libraries
	# binary will be at ~/bin/ffmpeg

	sudo apt update && sudo apt upgrade -y

	mkdir -p ~/ffmpeg_sources ~/bin
	export PATH="$HOME/bin:$PATH"

	## extract audio from .avi as .aac (conversion from another audio codec)
	ffmpeg -i foo.avi -acodec aac -ab 128k -strict experimental bar.aac

	## extract audio from .avi as .mp3 (no conversion, just copy)
	ffmpeg -i foo.avi -acodec copy bar.mp3

	## convert .mp3 to .aac
	ffmpeg -i foo.mp3 -acodec aac -ab 128k -strict experimental bar.aac

	## extract single frame as image from .mp4

	package main

	import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"strings"