martin fridrich martinfridrich

Vim without NERD tree or CtrlP

I used to use NERD tree for quite a while, then switched to CtrlP for something a little more lightweight. My setup now includes zero file browser or tree view, and instead uses native Vim fuzzy search and auto-directory switching.

Fuzzy Search

There is a super sweet feature in Vim whereby you can fuzzy find your files using **/*, e.g.:

:vs **/*<partial file name><Tab>

Himawari-8 animation tutorial

Here’s how to make animations like this one. It requires intermediate Unix command-line knowledge, to install some tools and to debug if they don’t work. You’ll need these utilities:

curl (or you can translate to wget)
convert and montage, part of ImageMagick
ffmpeg, plus whatever codecs
parallel, for iteration that’s nicer than shell for loops or xargs
run everything in zsh for leading 0s in numerical ranges to work

The standard names for indexes in PostgreSQL are:

{tablename}_{columnname(s)}_{suffix}

where the suffix is one of the following:

pkey for a Primary Key constraint;

key for a Unique constraint;

excl for an Exclusion constraint;

idx for any other kind of index;

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

Node.js Resources

What is node.js?

Node.js is just JavaScript running on the server side. That's it. That's all there is to it.

Express

Express Docs, if you want to get started and already know JavaScript this is the place to be

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

	#!/boot/bzImage

	# Linux kernel userspace initialization code, translated to bash
	# (Minus floppy disk handling, because seriously, it's 2017.)
	# Not 100% accurate, but gives you a good idea of how kernel init works
	# GPLv2, Copyright 2017 Hector Martin <marcan@marcan.st>
	# Based on Linux 4.10-rc2.

	# Note: pretend chroot is a builtin and affects the current process
	# Note: kernel actually uses major/minor device numbers instead of device name

	function params(fn) {
	var str = fn.toString();
	var sig = str.match(/\(([^)]*)\)/)[1];
	if (!sig) return [];
	return sig.split(', ');
	}

	console.api = function(obj){
	console.log();
	var proto = Object.getPrototypeOf(obj);

	/**
	* Module dependencies.
	*/

	var express = require('express')
	, routes = require('./routes')
	, cluster = require('cluster');

	var app = module.exports = express.createServer()
	, io = require('./socket')(app);

	//app.js Socket IO Test
	var app = require('express').createServer(),
	redis = require('socket.io/node_modules/redis'),
	io = require('socket.io').listen(app);

	var pub = redis.createClient(port, "url");
	var sub = redis.createClient(port, "url");
	var store = redis.createClient(port, "url");
	pub.auth('pass', function(){console.log("adentro! pub")});
	sub.auth('pass', function(){console.log("adentro! sub")});