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See https://www.pragmaticlinux.com/2020/10/start-a-virtualbox-vm-on-boot-with-systemd/

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# @brief Helper to read key value pairs
# @details
# Read kv in the form <key>=<value>
# The script cleans whitespaces first and will remove any newlines
# @see https://stackoverflow.com/a/27918723/1267320
read_kvp()
{
  file="$1"
  while IFS="=" read -r key value; do
    # clean whitespaces

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C++ : Polymorphic inheritance without vtable

Inheritance and Virtual Table are often used to create interface in C++ polymorphic class
What if ... there were another way to do this ?
easier, cleaner, faster and more reliable
This article explains how to use CRTP, [std::variant](https://en.cppreference.com/w/cpp/utility/variant and std::visit to increase code performance.

Table of content

1. Introduction

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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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zfs list -H -o name -t snapshot | xargs -n1 zfs destroy

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$ zfs destroy -nv system/usr/jails@BeforeUpgradingBaseJailFrom9.1To9.3
would destroy system/usr/jails/pg93@BeforeUpgradingBaseJailFrom9.1To9.3
would destroy system/usr/jails/mysql55@BeforeUpgradingBaseJailFrom9.1To9.3
would destroy system/usr/jails/pg94@BeforeUpgradingBaseJailFrom9.1To9.3
would destroy system/usr/jails/empty@BeforeUpgradingBaseJailFrom9.1To9.3
would destroy system/usr/jails/toiler@BeforeUpgradingBaseJailFrom9.1To9.3
would destroy system/usr/jails/pg90@BeforeUpgradingBaseJailFrom9.1To9.3
would destroy system/usr/jails/ansible@BeforeUpgradingBaseJailFrom9.1To9.3
would destroy system/usr/jails/snapshots@BeforeUpgradingBaseJailFrom9.1To9.3
would destroy system/usr/jails/ansible-slave@BeforeUpgradingBaseJailFrom9.1To9.3

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Renew GPG key

Given that your key has expired.

$ gpg --list-keys
$ gpg --edit-key KEYID

Use the expire command to set a new expire date:

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#include <X11/Xlib.h>
#include <stdio.h>
#include <stdlib.h>
 
int main()
{
    Display *display;
    Window window;
    XEvent event;
    int s;

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#!/bin/sh

MODEM="$(mmcli -L | grep -o '/org/freedesktop/ModemManager1/Modem/[0-9]*' | head -1)"
BEARER="$(mmcli -m $MODEM --list-bearers | grep -o '/org/freedesktop/ModemManager1/Bearer/[0-9]*' | head -1)"

mkdir -p /run/systemd/network
connect() {
  MODEM="$(mmcli -L | grep -o '/org/freedesktop/ModemManager1/Modem/[0-9]*' | head -1)"

  # hardcode all the things !! (this is for mobile vikings)

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Virtual Serial Ports

We can use socat to create 2 virtual serial ports that are connected to each other locally. This can be useful for debugging serial port applications. Or simulating serial port communication. Or running 2 legacy programs that only communicate with each other over serial ports, such as old DOS games. And of course, for education, since serial communication is probably the most simple communication protocol there is, RS232 is considered at the bottom of the OSI stack, at the "Physical Layer". See: http://electronics.stackexchange.com/questions/31171/internet-vs-serial-communication