Archiv der Kategorie: HowTo

Read Windows licence serial from UEFI Bios

For hardware with preinstalled (OEM) Windows 8.x and Windows 10, buyers don’t get a valid key printed on the device’s back or under the battery (for notebooks). The windows installer doesn’t even ask for a key anymore or the answer is skippable. If you still want to know your key to validate your fresh installation (on another pc) you can read it using the acpidump command under linux. For ubuntu install the package with:

sudo aptitude install acpidump

and read your serial with:

sudo acpidump -n MSDM

Root login on debian mariadb

Debian switched to mariadb by default. On a new installation you can login to your mysql database as root just by executing the mysql command without a password.

root@host:~# mysql
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 56339
Server version: 10.1.26-MariaDB-0+deb9u1 Debian 9.1

Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.

Type ‚help;‘ or ‚\h‘ for help. Type ‚\c‘ to clear the current input statement.

MariaDB [(none)]>

This is or can be a nice security feature. Connecting as root is only allowed by the root system user through the mysql unix socket. On the other hand you may have some software which needs the root user to access the database server. In this case you need to tweak some user settings.

First, set a password.

MariaDB [(none)]> update mysql.user set password=password(‚geheim‘) where user=’root‘;
MariaDB [(none)]> flush privileges;

Next, change the connection type.

MariaDB [(none)]> update mysql.user set plugin=“ where user=’root‘;
MariaDB [(none)]> flush privileges;

Downside seems to be the init process and autostart procedure. If you set a password for the root account, you need to add it to your /etc/mysql/debian.cnf in cleartext. Maybe you might want to consider this. Better choice would be to create a second privileged user.

Building a cross-platform app with Apache Cordova, Ionic 3, AngularFire 2, Angular 4 and Google Firebase

After reading about 50234 different tutorials, I decided to write down the steps for a development environment on Ubuntu 16.

Install node.js. Minimum version 6. Here for Ubuntu.

The first two commands to reset/cleanup your global installation. Also make sure, there is no old binary in /usr/local/bin/.

$ sudo aptitude purge nodejs
$ sudo rm -r /usr/lib/node_modules
$ curl -sL | sudo -E bash -
$ sudo aptitude install nodejs

Also install the SDKs for your target platforms. Android or iOS.

Install the needed packages (-g for global installation).
$ sudo npm install -g ionic@latest cordova typescript typings

Your system should look anything like this:

$ ionic info
Your system information:
Cordova CLI: 7.0.0
Ionic CLI Version: 2.2.3
Ionic App Lib Version: 2.2.1
ios-deploy version: Not installed
ios-sim version: Not installed
OS: Linux 4.4
Node Version: v6.10.3
Xcode version: Not installed

Create a new Ionic project. This will also create the project folder.
$ ionic start hybridapp blank --v2

where hybridapp is the name of the app and blank is a starter template layout (See $ ionic start –list for more examples). –v2 is needed to build the newest ionic version. Change into the project folder. This is your home now.

Install the needed npm packages (inside your project folder).

$ npm install firebase angularfire2 –save

Following this guide, I edited the package.json file. Not needed when using the correct ionic cli version.

Go to and create an account. Create a new project and select „Add Firebase to your web app“. Edit the file src/app/app.module.ts and add your details.

import { BrowserModule } from '@angular/platform-browser';
import { ErrorHandler, NgModule } from '@angular/core';
import { IonicApp, IonicErrorHandler, IonicModule } from 'ionic-angular';

import { AngularFireModule } from 'angularfire2';

import { MyApp } from './app.component';
import { HomePage } from '../pages/home/home';
import { ListPage } from '../pages/list/list';

import { StatusBar } from '@ionic-native/status-bar';
import { SplashScreen } from '@ionic-native/splash-screen';

export const firebaseConfig = {
apiKey: "your api key",
authDomain: "your domain",
databaseURL: "your url",
storageBucket: "your id",
messagingSenderId: "your id"

declarations: [
imports: [
bootstrap: [IonicApp],
entryComponents: [
providers: [
{provide: ErrorHandler, useClass: IonicErrorHandler}
export class AppModule {}

Try starting the setup with

$ npm run ionic:serve

If everything works, backup your files, commit to your git so you have a working base installation.

You can now start developing. Have fun.

Turn-by-turn navigation with a single click

I was always looking to start a navigation using Google Maps on Android with a just a single click. Of course you can set some presets or even a location, and since a few generations of Google now, there is even a navigation shortcut for your work or home address. But one thing, all these methods were missing: A real one click solution. Every shortcut only gets you to the calculated route, you always have to start the real navigation with another click.
Using tasker, I found a way to finally realize what i needed.
Tasker has support for intents and using the Google Maps-Intent works like a charm.

Create a new task.
Add System -> Send Intent
Action: android.intent.action.VIEW
Type: None
Data: google.navigation:q=location+you+look+for&mode=w


  • d for car (drive)
  • w for walk
  • b for bike

Take a look the the manual page for all options.

Fastes way to create a good looking webpage with node.js

If you need a responsive website to showcase something, here is a really fast way to do so.

Download a design you like from

$ mkdir node-html5
$ cd node-html5
$ npm init (just accept default settings)
$ npm install express --save

Extract the content of the design pack into the directory. Create index.js in the directory with the following content:

var express = require('express')
var path = require('path')
var PORT = 60000
var app = express()

app.use('/assets', express.static('assets'))
app.use('/images', express.static('images'))

app.get('/', function (req, res) {
res.sendFile(path.join(__dirname + '/index.html'))

app.listen(PORT, function () {
console.log('Listening on port: ' + PORT)

The directory should look like this:

├── assets
├── images
├── index.html
├── index.js
├── node_modules
├── package.json

Now edit the html, css and images like you want to.
Start the webserver with

$ node index.js

and point your browser to http://localhost:60000.

To deploy this setup e.g. to uberspace, see this post.

WordPress: HTTP Error 500 after plugin activation

After activating a wordpress plugin, the whole website went offline and the webserver showed an http error 500. You have to deactivate the plugin to access the site and the wp-admin interface again. You can do this either by editing the mysql database table or much simpler: By temporarily moving the plugins folder!
Just move the folder plugins in wp-contents to plugins.old, create an empty folder plugins, refresh the dashboard and click on Plugins. Remove the folder and move your plugins.old back to plugins. You have to activate all plugins again after this.


node.js webserver auf einem uberspace einrichten

Ich wollte mich schon länger mal mit node.js beschäftigen und einen einfachen Webdienst damit bauen. Es gibt im uberspace wiki einen kurzen Artikel zu nodejs und auch alle weiteren benötigten Informationen findet man dort irgendwo. Aber man muss sich doch alles zusammen suchen. Deswegen hiermal alle Punkte zusammengefasst, die man beachten muss, um einen einfachen Prototyp bei den ubernauten zu betreiben.

node.js Version

Mit dem Befehl

$ node -v

kann man sich die aktuell verwendete nodejs Version anzeigen lassen. Diese ist im Normalfall sehr alt. Um beim Aufruf von node eine aktuelle Version zu verwenden, ändern wir den Pfad. Alle verfügbaren installierten Versionen kann man sich anzeigen lassen:

$ ls -ld /package/host/localhost/nodejs-*

In der ~/.bash_profile fügt man in der letzten Zeile die gewünschte Version ein. z.B. 6

$ export PATH=/package/host/localhost/nodejs-6/bin:$PATH

Umgebungsvariable mit source ~/.bash_profile neuladen. Anschließend sollte die korrekte Version benutzt werden.

$ node -v

Einfacher node.js webserver

Da wir nicht die einzigen auf dem uberspace host sind und die gängigen Ports 80 und 443 bereits vom Apachen verwendet werden, müssen wir unseren node.js server auf einem anderen Port starten und leiten dann die Anfragen an Port 80 an diesen um. Der Port sollte zwischen 61000 und 65535 liegen. Wir suchen uns einen aus (hier 61003) und überprüfen, ob dieser schon belegt ist:

$ /usr/sbin/ss -ln | fgrep 61003

Bekommen wir keinen Eintrag angezeigt, können wir diesen Port verwenden. Die Weiterleitung richten wir mit einer .htaccess Datei in ~/html/ ein:

RewriteEngine On
RewriteRule ^(.*) http://localhost:61003/$1 [P]

Jetzt können wir loslegen. Wir wechseln in unseren DocumentRoot und installieren das node express.js modul für einen Webserver.

$ cd ~/html
$ npm install express

Als nächstes erstellen wir die Datei index.js mit folgenden Inhalt (den Port entsprechend anpassen):

var express = require('express');

var app = express();
app.set('port', (process.env.PORT || 61003));

app.get('/', function (req, res) {
  res.send('Hello World!')

var server = app.listen(app.get('port'), function () {
 console.log('Started on port %s', app.get('port'));

Der Webserver kann nun testweise mit

node index.js

gestartet werden und ein Aufruf der eigenen uberspace url im Browser sollte ein „Hello World!“ anzeigen. Schon fertig!

Naja, fast. Wir möchten ja, dass der Dienst zukünftig auch läuft, wenn wir nicht angemeldet sind. Also müssen wir unseren Server nun als Dienst einrichten.

Als Dienst einrichten

Dem uberspace wiki folgend erstellen wir als nächstes einen Dienst. Dafür zuerst den supervisor aktivieren und anschließend den Dienst hinzufügen. Hier heißt dieser einfach nodetest. 

$ test -d ~/service || uberspace-setup-svscan 
$ uberspace-setup-service nodetest node ~/html/index.js

Dem tool uberspace-setup-service übergibt man als 1. Parameter den Name des neuen Dienstes (nodetest) und als 2. Parameter das Kommando (node ~/html/index.js). Das Ergebnis schauen wir uns gleich an. Solltet ihr das ganze testen wollen oder geht irgendetwas schief, könnt ihr so den Dienst wieder löschen:

$ cd ~/service/nodetest
$ rm ~/service/nodetest
$ svc -dx . log
$ rm -rf ~/etc/run-nodetest

Für jeden Dienst wird in ~/service ein eigener Unterordner erzeugt. Hier liegt die run Datei, welche den eigentlich Aufruf beinhaltet und die Logdateien. Seit ihr dem Artikel genau gefolgt, sollte die letzte Zeile mit dem Aufruf der ~/service/nodetest/run so aussehen:

exec /package/host/localhost/nodejs-6/bin/node /home/user/html/index.js 2>&1

Das node als 2. Parameter wurde durch den gesammten Pfad ersetzt. Möchte man das nicht und will lieber immer die eingestellte Version verwenden, den Pfad entfernen und nur node verwenden.

Gesteuert wird der Dienst mit dem tool svc. Die wichtigsten Parameter:

-u up, also Dienst starten
-d down, also Dienst beenden
-h hup, ein HUP-Signal senden (Reload)

Ein Neustart des Dienstes sähe z.B. so aus:

$ svc -du ~/service/nodetest


Das entsprechende Log des Dienstes können wir recht einfach lesen. Mit dieser kleinen Funktion in der ~/.bashrc wird es aber noch einfacher:

        if [ -n "$1" ]; then
                zcat -f ~/service/$1/log/main/* | tai64nlocal | less;
                echo "Usage: readlog <daemonname>";

Der Aufruf geschieht dann mit:

$ readlog nodetest

COPS – Another OPDS catalog

The setup using the owncloud app described here works really well. Unless you want to share your books and catalog with someone else and you use the owncloud user also for other stuff and files. Of course it would be possible to create a special books-user and share the folder with other users etc., but this is to complex for my single user installation. Looking for a ebook reader addon, I found COPS – Calibre OPDS (and HTML) PHP Server. COPS generates an OPDS catalog using multiple sorting features and provides a search function. It also includes an ebook reader.

Install some needed packages.

sudo aptitude install php5-gd php5-sqlite php5-json php5-intl

Download the latest version from github.
I created a new subfolder in the webserver’s document root under /var/www/cops/ and extracted the files.

Copy the example configuration.

sudo cp /var/www/cops/config_local.php.example /var/www/cops/config_local.php

Edit the config file and change the path to your ebook directory containing the metadata.db from calibre.

$config['calibre_directory'] = '/media/usb/owncloud/user/files/ebooks/';

Edit your nginx configuration to password-protect your book collection. Add the section to your server configuration.

location /cops {
auth_basic "Restricted";
auth_basic_user_file /etc/nginx/.htpasswd;

Generate the .htpasswd file with your tool of choice. For testing use an online generator.

Point your browser to the encrypted SSL version of your url like https://yourip/cops. It should ask for a username and password and after correct credentials, show you your collection. To use the catalog with an app like FBReader, you need to apend feed.php to the url like https://yourip/cops/feed.php.cops



Replace harddisk to grow raid and lvm volume

I ran out of disk space on a 2 disk raid mirror. I already replaced one of the harddisks with a bigger 4TB one. The size doesn’t allow for MBR anymore and I needed to switch to GPT. The now smaller drive is also to replaced. Here are some of my notes for the procedure for later use. In the end I didn’t use this guide. I had a good backup and some time on the weekend as nobody needed the server, so I opted for the live migration. Since I already wrote most of the steps down, I will keep it and just add some notes at the end.

Mark the smaller disk as failed and remove it from the array.
mdadm --manage /dev/md0 --fail /dev/sda1
mdadm --manage /dev/md1 --fail /dev/sda2
mdadm --manage /dev/md2 --fail /dev/sda3
cat /proc/mdstat
mdadm --manage /dev/md0 --remove /dev/sda1
mdadm --manage /dev/md1 --remove /dev/sda2
mdadm --manage /dev/md2 --remove /dev/sda3

Shutdown the system, replace harddisk with new one and boot a live system. Install the needed packages.
aptitude install mdadm gdisk
modprobe raid1

Start raid.
mdadm --examine --scan >> /etc/mdadm/mdadm.conf

Clone the GPT partition schema to the new disk.
sgdisk --backup=table /dev/sdb
sgdisk --load-backup=table /dev/sda
sgdisk -G /dev/sda

Add to raid
mdadm --manage /dev/md0 --add /dev/sda1
mdadm --manage /dev/md1 --add /dev/sda2
mdadm --manage /dev/md2 --add /dev/sda3

Synchronisation starts. You can watch the process with
watch cat /proc/mdstat

Expand the raid to the new maximum size.
mdadm --grow /dev/md2 --size=max

Grow the LVM.
pvresize /dev/md2
lvextend -L +1TB /dev/mapper/deb7-home
resize2fs /dev/mapper/deb7-home
grub-install /dev/sdc --recheck


Manual integrity-check of raid.
/usr/share/mdadm/checkarray /dev/md0
/usr/share/mdadm/checkarray /dev/md1
/usr/share/mdadm/checkarray /dev/md2


Alternative: Live migration

Live migration is nearly the same, but you don’t have to reboot the system.

Hotplug the new (third) drive to your system. If the Sata-controller is set to AHCI mode, the system should recognize the new drive.

After cloning the partition table with sgdisk, add the drive to the raid.
mdadm /dev/md0 --manage --add /dev/sdc1
mdadm /dev/md1 --manage --add /dev/sdc2
mdadm /dev/md2 --manage --add /dev/sdc5

Grow the raid to 3 devices and let it recover.
mdadm /dev/md0 --grow -n3
mdadm /dev/md1 --grow -n3
mdadm /dev/md2 --grow -n3

Mark the to-be-replaced drive as failed and remove it from the raid array.
mdadm /dev/md0 --manage -f /dev/sda1 -r /dev/sda1
mdadm /dev/md1 --manage -f /dev/sda2 -r /dev/sda2
mdadm /dev/md2 --manage -f /dev/sda3 -r /dev/sda3

Shrink the array again to 2 drives.
mdadm /dev/md0 --grow -n2
mdadm /dev/md1 --grow -n2
mdadm /dev/md2 --grow -n2

Grow the raid and extend pv, lv and filesystem like above.

OPDS catalog in owncloud

A few ebook reader apps are able to connect to an OPDS catalog and fetch books from there directly. Since I store all my calibre-managed ebooks on my owncloud share, it would be nice to automatically generate such a catalog. Frank de Lange has built a plugin for owncloud to do just that. You can find it in his github or here.

To install, download the files and unzip them into the owncloud/apps/ directory.

After that change the directory permissions:

sudo chmod -R 750  /var/www/owncloud/apps/files_opds/

You also have to app the option

„appcodechecker“ => false

to your config.php. You can then activate the extension in the apps menu.

Visit the administration page and check your settings (defaults should be fine). After that change to your personal settings. Edit the directory containing your ebooks. Make sure, you don’t add a backslash at the end of the path. This one took me some time to figure out.

Root directory: /documents/ebooks

Click the „Schedule rescan“ button. After that you can access your OPDS catalog using your owncloud login at the url


Chrome doesn’t know what to do with the data, but firefox displays the catalog nicely.