Alex DeLorenzo alexdelorenzo

Overview

Some notes about:

Explaining why current day Linux memory swap thrashing still happens (as of 2016).
Mitigating "stop the world" type thrashing issues on a Linux workstation when it's under high memory pressure and where responsiveness is more important than process completion.
Prioritizing and limiting memory use.
Older ulimit versus newer CGroup options.

These notes assume some basic background knowledge about memory management, ulimits and cgroups.

Bash Shortcuts

Moving

command	description
ctrl + a	Goto BEGINNING of command line

Operational PGP

This is a guide on how to email securely.

There are many guides on how to install and use PGP to encrypt email. This is not one of them. This is a guide on secure communication using email with PGP encryption. If you are not familiar with PGP, please read another guide first. If you are comfortable using PGP to encrypt and decrypt emails, this guide will raise your security to the next level.

Problem: When linking to the raw version of a gist, the link changes with each revision.

Solution:

To return the first file from a gist: https://gist.github.com/[gist_user]/[gist_id]/raw/

Example: https://gist.github.com/atenni/5604522/raw/
Works even when you change the filename.

To get a file from multi–file gist: https://gist.github.com/[gist_user]/[gist_id]/raw/[file_name]

	Ansible playbook to setup HTTPS using Let's encrypt on nginx.

	The Ansible playbook installs everything needed to serve static files from a nginx server over HTTPS.
	The server pass A rating on [SSL Labs](https://www.ssllabs.com/).

	To use:
	1. Install [Ansible](https://www.ansible.com/)
	2. Setup an Ubuntu 16.04 server accessible over ssh
	3. Create `/etc/ansible/hosts` according to template below and change example.com to your domain
	4. Copy the rest of the files to an empty directory (`playbook.yml` in the root of that folder and the rest in the `templates` subfolder)

	Compiling a Linux kernel on Ubuntu
	----------------------------------

	This should be useful in the event that the user wants to investigate whether a newer kernel allows
	certain peripherals to work better (or at all) or some other problems they might encounter while using
	the kernel officially provided by Canonical.

	As an example, I use the 4.1.5 release from kernel.org.

	1) Make sure you have the build environment set up first:

	# You should really be using this one instead, SERIOUS
	# https://gist.github.com/pudquick/ac8f22326f095ed2690e

	from ctypes import Structure, POINTER, CDLL, c_char_p, c_int32, create_string_buffer
	from ctypes.util import find_library

	# We build an opaque object pointer class type to safely handle data without inspecting it
	class OpaqueType(Structure):
	pass

	"""
	This creates the following GIF, where the text appears to be "embedded"
	in the video and "disappears" behind rapunzel.

	http://i.imgur.com/gxEHfLX.gif
	"""

	from moviepy.editor import *
	import numpy as np
	import skimage.morphology as skm

	#!/usr/bin/env zsh

	# Initialize VPN
	sudo vpnns up
	sudo vpnns start_vpn

	# Popcorn time!
	sudo ip netns exec frootvpn sudo -u $USER popcorntime

	# Cleanup

	Guide & Discussion Thread:

	http://forum.netkas.org/index.php?topic=874.0
	http://forum.netkas.org/index.php?action=printpage;topic=874.0

	For the best guide, use search keyword: chmod. Scrolls down to -->
	Post by: Shinso on September 18, 2012, 07:28:35 PM
	Post by: Shinso on September 18, 2012, 07:30:19 PM

	* First: upgrade cpu to Core2Duo