Dean Jackson deanishe

ZSH CheatSheet

This is a cheat sheet for how to perform various actions to ZSH, which can be tricky to find on the web as the syntax is not intuitive and it is generally not very well-documented.

Strings

Description	Syntax
Get the length of a string	`${#VARNAME}`
Get a single character	`${VARNAME[index]}`

Chaining promises

Chaining promises in ClojureScript is best done using the thread-first macro, ->. Here's an example of using the fetch API:

(-> (js/fetch "/data")
    (.then (fn [r]
             (when-not (.-ok r)
               (throw (js/Error. "Could not fetch /data")))
             (.json r)))

How to use asynchronous generators

The documentation 6.2.9.4. "Asynchronous generator-iterator methods" is phrased really ambiguously. To make matters worse, typing.AsyncGenerator is not specified fully correctly.

Here, I attempt to more clearly capture the actual interface contract, based on what I've read and observed. See also PEP 492 -- Coroutines with async and await syntax and PEP 525 -- Asynchronous Generators.

This might be useful to implement lower-level behaviors than you can with async for, like sending values into the generator function.

TSend = TypeVar('TSend', contravariant=True)

ANSI Escape Sequences

Standard escape codes are prefixed with Escape:

Ctrl-Key: ^[
Octal: \033
Unicode: \u001b
Hexadecimal: \x1B
Decimal: 27

security and hardening options for systemd service units

A common and reliable pattern in service unit files is thus:

NoNewPrivileges=yes
PrivateTmp=yes
PrivateDevices=yes
DevicePolicy=closed
ProtectSystem=strict

Extract Subtitles From mkv

Instuctions available (moved) at REMOTE ORIGIN website: Extract Subtitles From mkv

Opening and closing an SSH tunnel in a shell script the smart way

I recently had the following problem:

From an unattended shell script (called by Jenkins), run a command-line tool that accesses the MySQL database on another host.
That tool doesn't know that the database is on another host, plus the MySQL port on that host is firewalled and not accessible from other machines.

We didn't want to open the MySQL port to the network, but it's possible to SSH from the Jenkins machine to the MySQL machine. So, basically you would do something like

ssh -L 3306:localhost:3306 remotehost

	#!/bin/sh
	#_(

	#_DEPS is same format as deps.edn. Multiline is okay.
	DEPS='
	{:deps {clj-time {:mvn/version "0.14.2"}}}
	'

	#_You can put other options here
	OPTS='

	#!/usr/bin/osascript -l JavaScript

	ObjC.import('Cocoa')

	app = Application.currentApplication()
	app.includeStandardAdditions = true

	ObjC.registerSubclass({
	name: 'MenuAction',
	methods: {

	# FontInstaller (by @olemoritz)

	# This script installs a custom TTF font on iOS (system-wide).
	# It can be used in one of two ways:

	# 1. Simply run it in Pythonista, you'll be prompted for the URL of the font
	# you'd like to install (if there's a URL in the clipboard, it'll be used by default)

	# 2. Use it as an 'Open in...' handler, i.e. select this file in Pythonista's 'Open in...
	# menu' setting. This way, you can simply download a ttf file in Safari and open it in