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dnsmasq from package 'dnsmasq-base' starts with a (from libvirt) generated configuration: /var/lib/libvirt/dnsmasq/default.conf.
this configuration file is not directly editable because it gets overwritten from libvirt.
there is no possibility to set 'no-dhcp-interface=eth0' per 'libvirt'.
 
# ###########################################################
# deactivate dhcp in dnsmasq per libvirt
 
# dnsmasq listen on port 53 (dns) and 67 (dhcp)
j@ubuntu:~$ sudo netstat -taupen | grep -E ':53|:67'
tcp 0 0 192.168.122.1:53 0.0.0.0:* LISTEN 0 9817 1218/dnsmasq

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#
# if you are using RVM installed system wide (root)
# REMEMBER: if you are using RVM system wide NEVER run sudo gem install !!!!
#

rvmsudo gem install rspec rspec-rails rspec-rails-matchers

#
# if you are using RVM only on your local user or not using RVM at all
#

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Ruby on Rails Cheatsheet

Architecture

Create a new application

Install the Rails gem if you haven't done so before

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# Puma can serve each request in a thread from an internal thread pool.
# The `threads` method setting takes two numbers: a minimum and maximum.
# Any libraries that use thread pools should be configured to match
# the maximum value specified for Puma. Default is set to 5 threads for minimum
# and maximum; this matches the default thread size of Active Record.
# More: https://devcenter.heroku.com/articles/deploying-rails-applications-with-the-puma-web-server#threads
#
threads_count = ENV.fetch("RAILS_MAX_THREADS") { 5 }
threads threads_count, threads_count

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desc 'Stop rails server'
task :stop do
  File.new("tmp/pids/server.pid").tap { |f| Process.kill 9, f.read.to_i }.delete
end

desc 'Starts rails server'
task :start do
  Process.exec("rails s puma -d")
end

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Automatically push an updated file whenever it is changed

Linux

1. Make sure inotify-tools is installed (https://github.com/rvoicilas/inotify-tools)
2. Configure git as usual
3. Clone the git repository of interest from github and, if necessary, add file you want to monitor
4. Allow username/password to be cached so you aren't asked everytime

git config credential.helper store

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Originall From: Posted 2015-05-29 http://ubwg.net/b/full-list-of-ffmpeg-flags-and-options

This is the complete list that’s outputted by ffmpeg when running ffmpeg -h full.

usage: ffmpeg [options] [[infile options] -i infile]… {[outfile options] outfile}…

Getting help:
    -h — print basic options
    -h long — print more options
    -h full — print all options (including all format and codec specific options, very long)

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Google Public NTP [AS15169]:

time.google.com

time1.google.com

time2.google.com

time3.google.com

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Setting up Qemu with a tap interface

There are two parts to networking within QEMU:

• The virtual network device that is provided to the guest (e.g. a PCI network card).
• The network backend that interacts with the emulated NIC (e.g. puts packets onto the host's network).

Example: User mode network

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#!/bin/bash
#
# Digital Ocean Ubuntu 16.04.6 Droplet
# Running:
# wget https://gist.githubusercontent.com/stroebs/54fc09734a3911e91eeeb43434f117df/raw/1ede2fb162d404171122db0c84a9eeea468a92cd/make-chr.sh
# chmod +x make-chr.sh
# ./make-chr.sh
#
wget http://download2.mikrotik.com/routeros/6.37/chr-6.37.img.zip -O chr.img.zip  && \
gunzip -c chr.img.zip > chr.img  && \