Heechul Ryu ryuheechul

ANSI Escape Sequences

Standard escape codes are prefixed with Escape:

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

Seamlessly editing remote files in (Neo)Vim with Netrw and scp

Neovim and Vim both come bundled with a standard plugin called Netrw. Netrw acts a file explorer (similar to NERDTree), but more importantly has the ability to work with scp (as well as sftp, rcp, ftp, and lots of others :h netrw-nread) to let you edit files and browse directories that are hosted on a remote machine, inside of your local Vim instance.

This is useful since you are able to use your Vim setup and plugins without copying over your dotfiles to the remote machine. As well, since the file is copied to your local machine, there will be no delay when typing.

Setup

This is optional for Vim, but required for Neovim (check this Neovim issue explaining why).

X11 Forwarding using an SSH Reverse Tunnel

X11 Forwarding is very useful when you want to run GUI based applications on a remote machine. I needed it to run IntelliJ IDE on HPC. But while X11 forwarding can be easily enabled using the -X (or -Y) option of ssh, it doesn't work if xauth is not installed on the remote server - in my case the HPC compute nodes. In this case, ssh can be used to create a reverse tunnel from the remote server to the local machine. X11Forwarding can then be done by setting the display on the remote server as the entry port of the tunnel and making the X-server listen on the exit port of the tunnel in the local machine.

Here I'll describe how I went about creating a SSH reverse tunnel from HPC compute nodes to my local machine and used that to enable X11 Forwarding. As a prerequisite, I assume that a Display Manager that launches the X-server is installed on the local machine. Popular ones are XQuartz for macOS and XMing for Windows.

Enable X11 forwarding on local machine.

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0.1. References
0.2. Other cheatsheets
0.3. Manage multiple gcloud config configurations
- 0.3.1. Switch gcloud context with gcloud config
0.4. Credentials
0.5. info
0.6. projects
0.7. zones & regions
0.8. Organization
0.9. billing

Simple vsock setup for QEMU

Configuration

Host Kernel: rawhide 4.13.0-0.rc6.git4.2.fc28.x86_64 (on Fedora 24)

QEMU is mainline built from sources: QEMU emulator version 2.10.50 (v2.10.0-105-g223cd0e)

Guest: clear-17460-kvm.img (which has vsock support)

Electron apps

Slide deck frameworks supporting Markdown source

	#!/bin/bash -e

	# Usage ./k8s-service-account-kubeconfig.sh ( namespace ) ( service account name )

	TEMPDIR=$( mktemp -d )

	trap "{ rm -rf $TEMPDIR ; exit 255; }" EXIT

	SA_SECRET=$( kubectl get sa -n $1 $2 -o jsonpath='{.secrets[0].name}' )

	const puppeteer = require('puppeteer');

	(async () => {

	const browser = await puppeteer.launch();
	const page = await browser.newPage();
	// Adjustments particular to this page to ensure we hit desktop breakpoint.
	page.setViewport({width: 1000, height: 600, deviceScaleFactor: 1});

	await page.goto('https://www.chromestatus.com/samples', {waitUntil: 'networkidle'});

	# Prometheus configuration to scrape Kubernetes outside the cluster
	# Change master_ip and api_password to match your master server address and admin password
	global:
	scrape_interval: 15s
	evaluation_interval: 15s


	scrape_configs:
	# metrics for the prometheus server
	- job_name: 'prometheus'