Abhinav Ra abvr

Enable nested virtualization in KVM

For those times when you need to run virtualization (e.g. vagrant with VirtualBox) inside a KVM (libvirtd) guest.

The following taken from Enabling nested virtualization in KVM over on Fedora Docs.

Make sure that the Intel-VT-x/AMD-V extensions are enabled in the host machine's BIOS. For Intel:

Latency Comparison Numbers (~2012)

Name
L1 cache reference	0.5	ns
Branch mispredict	5	ns
L2 cachereference	7	ns			14x L1 cache
Mutex lock/unlock	25	ns
Main memory reference	100	ns			20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy	3,000	ns	3	us

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;

Linux Command Cheatsheet

Linux Keyboard shortcuts

open terminal: Ctrl+Alt+T

Ctrl + C is used to kill a process with signal SIGINT , in other words it is a polite kill .

Ctrl + Z is used to suspend a process by sending it the signal SIGTSTP , which is like a sleep signal, that can be undone and the process can be resumed again.

README

Create a template service file at /etc/systemd/system/[email protected]. The template parameter will correspond to the name of target host:

[Unit]
Description=Setup a secure tunnel to %I
After=network.target

How does `ls` work?

I wanted to be really able to explain to a fair amount of detail how does the program :command:`ls` actually work right from the moment you type the command name and hit ENTER. What goes on in user space and and in kernel space? This is my attempt and what I have learned so far on Linux (Fedora 19, 3.x kernel).

How does the shell find the location of 'ls' ?

	/*
	Unfollow (stop following) those people who are not following you back on Twitter (or unfollow everyone if desired).

	This will work for new Twitter web site code structure (it was changed from July 2019, causing other unfollow-scripts to stop working).

	Instructions:
	1) The code may need to be modified depending on the language of your Twitter web site:
	* For English language web site, no modification needed.
	* For Spanish language web site, remember to set the 'LANGUAGE' variable to "ES".
	* For another language, remember to set the 'LANGUAGE' variable to that language and modify the 'WORDS' object to add the words in that language.

	#!/bin/bash

	set -o nounset
	set -o errexit

	[[ ! -z ${DEV} ]] \|\| { echo "DEV is not defined"; exit 1; }

	# for each dir in DEV
	checkouts=$(find $DEV -maxdepth 1 -type d)
	for dir in ${checkouts}; do

	#!/usr/bin/env python3
	#
	# Dumb script to dump (some) of bcache status
	# Copyright 2013 Darrick J. Wong. All rights reserved.
	#
	# This file is part of Bcache. Bcache is free software: you can
	# redistribute it and/or modify it under the terms of the GNU General Public
	# License as published by the Free Software Foundation, version 2.
	#
	# This program is distributed in the hope that it will be useful, but WITHOUT

	##############
	# Xft settings
	##############

	Xft.dpi: 96
	Xft.antialias: true
	Xft.rgba: rgb
	Xft.hinting: true
	Xft.hintstyle: hintslight