hellerbarde

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

willurd

Each of these commands will run an ad hoc http static server in your current (or specified) directory, available at http://localhost:8000. Use this power wisely.

Discussion on reddit.

Python 2.x

$ python -m SimpleHTTPServer 8000

MawKKe

#!/usr/bin/env bash
# 
#    Author: Markus (MawKKe) ekkwam@gmail.com
#    Date: 2018-03-19
#
#
# What?
#
#    Linux dm-crypt + dm-integrity + dm-raid (RAID1) 
#

joshisa

#!/bin/bash
# Referenced and tweaked from http://stackoverflow.com/questions/6174220/parse-url-in-shell-script#6174447

proto="$(echo $1 | grep :// | sed -e's,^\(.*://\).*,\1,g')"
# remove the protocol
url="$(echo ${1/$proto/})"
# extract the user (if any)
userpass="$(echo $url | grep @ | cut -d@ -f1)"
pass="$(echo $userpass | grep : | cut -d: -f2)"
if [ -n "$pass" ]; then

gboudreau

Generating Authy passwords on other authenticators

---

*update: TBC, but this new might affect how easy it is to use this technique past August 2024: Authy is shutting down its desktop app | The 2FA app Authy will only be available on Android and iOS starting in August

---

This gist, based in part on a gist by Brian Hartvigsen, allows you to export from Authy your TOTP tokens you have stored there.
Those can be "standard" 6-digits / 30 secs tokens, or Authy's own version, the 7-digits / 10 secs tokens.

dojoe

On systems with UEFI Secure Boot enabled, recent Linux kernels will only load signed modules, so it's about time DKMS grew the capability to sign modules it's building.

These scripts are extended and scriptified variants of https://computerlinguist.org/make-dkms-sign-kernel-modules-for-secure-boot-on-ubuntu-1604.html and https://askubuntu.com/questions/760671/could-not-load-vboxdrv-after-upgrade-to-ubuntu-16-04-and-i-want-to-keep-secur/768310#768310 and add some error checking, a passphrase around your signing key, and support for compressed modules.

dkms-sign-module is a wrapper for the more generic sign-modules which can also be used outside of DKMS.

Installation

1. Create a directory under /root, say /root/module-signing, put the three scripts below in there and make them executable: chmod u+x one-time-setup sign-modules dkms-sign-module

LeviSnoot

Discord Timestamps

Discord timestamps can be useful for specifying a date/time across multiple users time zones. They work with the Unix Timestamp format and can be posted by regular users as well as bots and applications.

The Epoch Unix Time Stamp Converter is a good way to quickly generate a timestamp. For the examples below I will be using the Time Stamp of 1543392060, which represents November 28th, 2018 at 09:01:00 hours for my local time zone (GMT+0100 Central European Standard Time).

Formatting

Style	Input	Output (12-hour clock)	Output (24-hour clock)
Default	<t:1543392060>	November 28, 2018 9:01 AM	28 November 2018 09:01

plentz

# to generate your dhparam.pem file, run in the terminal
openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048

dupuy

Markdown and reStructuredText

GitHub supports several lightweight markup languages for documentation; the most popular ones (generally, not just at GitHub) are Markdown and reStructuredText. Markdown is sometimes considered easier to use, and is often preferred when the purpose is simply to generate HTML. On the other hand, reStructuredText is more extensible and powerful, with native support (not just embedded HTML) for tables, as well as things like automatic generation of tables of contents.

digitaljhelms

Branching

Quick Legend

Description, Instructions, Notes

Instance	Branch