Stan Sobolev Jacke

macOS Internals

Understand your Mac and iPhone more deeply by tracing the evolution of Mac OS X from prelease to Swift. John Siracusa delivers the details.

Starting Points

How to use this gist

You've got two main options:

Bandwidth and Latency Testing

It's very useful to understand the bandwidth, throughput and latency of the remote computer you're trying to communicate with. It can inform you how well you can play a multiplayer game (latency), or the bitrate at which you can stream a video (throughput).

The difference between bandwidth and throughput is:

"A little bit of slope makes up for a lot of y-intercept"

01/13/2012. From a lecture by Professor John Ousterhout at Stanford, class CS140

Here's today's thought for the weekend. A little bit of slope makes up for a lot of Y-intercept.

[Laughter]

Here's a list of mildly interesting things about the C language that I learned mostly by consuming Clang's ASTs. Although surprises are getting sparser, I might continue to update this document over time.

There are many more mildly interesting features of C++, but the language is literally known for being weird, whereas C is usually considered smaller and simpler, so this is (almost) only about C.

1. Combined type and variable/field declaration, inside a struct scope [https://godbolt.org/g/Rh94Go]

struct foo {
   struct bar {
 int x;

	#!/usr/bin/env python
	import os
	import grp
	import sys
	import stat
	import time
	import hmac
	import boto3
	import tempfile

	#!/usr/bin/env bash

	# Read https://www.linode.com/docs/email/postfix/configure-spf-and-dkim-in-postfix-on-debian-8 first!
	# Run this script at the beginning of each month

	# (Optional) Email notification if the script is interrupted
	#function notify() {
	# printf 'Refer to the logs for further info.\n' \| mail -s 'DKIM rotation process was interrupted' '[email protected]'
	#}
	#

	Supported escape sequences:
	~. - terminate connection (and any multiplexed sessions)
	~B - send a BREAK to the remote system
	~C - open a command line
	~R - request rekey
	~V/v - decrease/increase verbosity (LogLevel)
	~^Z - suspend ssh
	~# - list forwarded connections
	~& - background ssh (when waiting for connections to terminate)
	~? - this message

	postgres@db:~/playground/rewinddemo$ initdb -D primary
	The files belonging to this database system will be owned by user "postgres".
	This user must also own the server process.

	The database cluster will be initialized with locale "en_US.utf8".
	The default database encoding has accordingly been set to "UTF8".
	The default text search configuration will be set to "english".

	Data page checksums are disabled.

	// I'm tired of extensions that automatically:
	// - show welcome pages / walkthroughs
	// - show release notes
	// - send telemetry
	// - recommend things
	//
	// This disables all of that stuff.
	// If you have more config, leave a comment so I can add it!!

	{

	CREATE UNLOGGED TABLE test_table (
	id bigint /primary key/ not null,

	text1 text not null, /* 1 KiB of random data */
	text2 text not null, /* 255 bytes of random data */

	/* cardinality columns */
	int1000 bigint not null, /* ranges 0..999, cardinality: 1000 */
	int100 bigint not null, /* 0..99, card: 100 */
	int10 bigint not null /* 0..10, card: 10 */