Syntax highlighting in LaTeX with lstlisting

When adding code snippets to my LaTeX documents, I use lstlisting. It is a syntax highlighting environment that can easily be tweaked to match your own styling.

LaTex listlisting syntax highlighting example

Example of syntax highlighting with lstlisting and the style defined below.

To do this you need to use the package listings\usepackage{listings}.

Code snippets are added like this:

Some super cool code snippet...

Adding a code snippet from file is also possible:


You can changes the styling of the code fragments (making keywords bold, comments italic, changing colors, …) by specifying lstset:

\lstset{ %
  backgroundcolor=\color{white},   % choose the background color; you must add \usepackage{color} or \usepackage{xcolor}
  basicstyle=\footnotesize,        % the size of the fonts that are used for the code
  breakatwhitespace=false,         % sets if automatic breaks should only happen at whitespace
  breaklines=true,                 % sets automatic line breaking
  captionpos=b,                    % sets the caption-position to bottom
  commentstyle=\color{commentsColor}\textit,    % comment style
  deletekeywords={...},            % if you want to delete keywords from the given language
  escapeinside={\%*}{*)},          % if you want to add LaTeX within your code
  extendedchars=true,              % lets you use non-ASCII characters; for 8-bits encodings only, does not work with UTF-8
  frame=tb,	                   	   % adds a frame around the code
  keepspaces=true,                 % keeps spaces in text, useful for keeping indentation of code (possibly needs columns=flexible)
  keywordstyle=\color{keywordsColor}\bfseries,       % keyword style
  language=Python,                 % the language of the code (can be overrided per snippet)
  otherkeywords={*,...},           % if you want to add more keywords to the set
  numbers=left,                    % where to put the line-numbers; possible values are (none, left, right)
  numbersep=5pt,                   % how far the line-numbers are from the code
  numberstyle=\tiny\color{commentsColor}, % the style that is used for the line-numbers
  rulecolor=\color{black},         % if not set, the frame-color may be changed on line-breaks within not-black text (e.g. comments (green here))
  showspaces=false,                % show spaces everywhere adding particular underscores; it overrides 'showstringspaces'
  showstringspaces=false,          % underline spaces within strings only
  showtabs=false,                  % show tabs within strings adding particular underscores
  stepnumber=1,                    % the step between two line-numbers. If it's 1, each line will be numbered
  stringstyle=\color{stringColor}, % string literal style
  tabsize=2,	                   % sets default tabsize to 2 spaces
  title=\lstname,                  % show the filename of files included with \lstinputlisting; also try caption instead of title
  columns=fixed                    % Using fixed column width (for e.g. nice alignment)

When you use your own colors, you must naturally define them:


\definecolor{commentsColor}{rgb}{0.497495, 0.497587, 0.497464}
\definecolor{keywordsColor}{rgb}{0.000000, 0.000000, 0.635294}
\definecolor{stringColor}{rgb}{0.558215, 0.000000, 0.135316}

If needed you can also specify your own language syntax:

  keywords={typeof, new, true, false, catch, function, return, null, catch, switch, var, if, in, while, do, else, case, break},
  ndkeywords={class, export, boolean, throw, implements, import, this},

More info can be found in the LaTeX documentation: Source Code Listings.

Configuring Jenkins on Ubuntu (for C++, GTest and Bitbucket)


$ sudo apt-get install jenkins

Once installed, Jenkins will run at port 8080 on your server.

  • Don’t forget to install a C/C++ compiler
  • Don’t forget to install dependencies like QT, libc++ and Boost



Before doing anything else, you must secure your installation.
Navigate to Jenkins, Manage Jenkins, Configure Global Security.

On this page you can specify all security settings. The most simple case is to use Jenkins’ own user database.
If you refresh the page after enabling this option, you will see a Register button in top right corner of the page. Create an account before proceeding.

Now you have an account, you can select Matrix-based security. This will show a list (matrix) of all security options. You can restrict the access for the anonymous user there.
You should add your account to the security matrix with administrator access before saving. Otherwise you will lock yourself out!
You can eventually add new users there with their own permissions.

Jenkins global security matrix

If you lock yourself out, you can manually disable security in /var/lib/jenkins/config.xml.
Change <useSecurity>true</useSecurity> to <useSecurity>false</useSecurity> and restart Jenkins: sudo service jenkins restart.

Adding build job

On some Jenkins installations you must install the Git plugin before you can use git as SCM.

SSH keys

We also need to configure SSH keys for Bitbucket so we don’t have to use plain text passwords.

$ ssh-keygen 
Generating public/private rsa key pair.
Enter file in which to save the key (/Users/Mathias/.ssh/id_rsa): 
/Users/Mathias/.ssh/id_rsa already exists.
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
passphrase too short: have 3 bytes, need > 4
Saving the key failed: /Users/Mathias/.ssh/id_rsa.
The key fingerprint is:
4c:72:6c:3a:7f:a6:45:80:92:e7:39:b7:73:7b:c6:51 Mathias@Mac-Pro-van-Mathias.local
The key's randomart image is:
+--[ RSA 2048]----+
|       . 0..E    |
|      o.o...     |
|      .+B. o.    |
|       *+oo.+    |
|      C So.=+    |
|          o=.    |
|         ..o     |
|                 |
|                 |

On Bitbucket go to Manage account, click SSH keys.
The SSH Keys page displays. If you have any existing keys, those appear on this page.
Back in your terminal, copy the contents of your public key file.

$ cat ~/.ssh/

More information on working with SSH keys (and Bitbucket) can be found here.

Add credentials to Jenkins

Now we have generated keys for our Git authentication, we can add them to the credentials in Jenkins.
On the built configuration screen select SSH username with private key for credentials.

Select your username, and Enter directly for the private key.
Again, you can get the key from the console, but this time we need the private key:

$ cat ~/.ssh/id_rsa

You also need to specify the passphrase (if you set one before).

Jenkins Credentials SSH key git
Configuring build triggers

Choose for Trigger builds remotely and specify a really random authentication token.
You can for example generate a random token using OpenSSL: $ openssl rand -base64 16.

You also need the API key from your Jenkins account. Go to your profile page and click on Configure. On the configuration page click on Show API Token.

Finally you can add trigger on Bitbucket. Go the repository’s settings page, and navigate to Services. Add a new Jenkins service with the following details:

  • Endpoint: Jenkins URL in the following format —
  • Project name: the project name that you’ve set in Jenkins
  • Token: the authentication token of the project (that we generated earlier).
Schermafbeelding 2015-10-18 om 19.06.31

If you now do a push to your Bitbucket remote repo, it will automatically trigger a Jenkins build.

Configuring build

If you want to build the project with CMake, you might have to install the CMake plugin (and you need CMake on your server).
Maybe you also need the Build Environment plugin.

Once installed, you click on Add build step and you choose CMake Build. You can also specify a Shell invocation if you want to use your own make file or build commands.

I won’t dig deeper into specific build settings, since that’s irrelevant for you particular project…

Configuring unit test (gtest)

If you use GoogleTest, you can create a test output report with Jenkins. Execute gTest with this flag: --gtest_output=xml:gtestresults.xml.

You also need to replace notun by skipped since Jenkins doesn’t like the first one.

awk '{ if ($1 == "<testcase" && match($0, "notrun")) print substr($0,0,length($0)-2) "><skipped/></testcase>"; else print $0;}' gtestresults.xml > gtestresults-skipped.xml
mv gtestresults.xml

Now you have the xml report file, you must add the Publish JUnit test result report Post-build action with the gtestresults-skipped.xml file.

Caddy Server and WordPress (PHP-FPM)

Caddy LogoRecently I discovered an amazing open source project: Caddy, a fully functional HTTP/2 webserver, written in Go.

Caddy is a lightweight, general-purpose web server for Windows, Mac, Linux, BSD, and Android. It is a capable alternative to other popular and easy to use web servers.

The most notable features are HTTP/2, Virtual Hosts, TLS + SNI, and easy configuration with a Caddyfile. Usually, you have one Caddyfile per site. Most directives for the Caddyfile invoke a layer of middleware which can be used in your own Go programs.

In this tutorial I will explain how to run WordPress with Caddy server (on Ubuntu), using Caddy’s FastCGI support and PHP-FPM (i.e. PHP FastCGI Process Manager). Of course you also need MySQL/MariaDB to run WordPress.


I assume that you have a MySQL server up and running (or that you have the knowledge to do so) .


Install PHP-FPM:

$ sudo apt-get install php5-fpm

PHP-FPM listens to FastCGI requests on a unix socket by default (on Ubuntu and Arch Linux): unix:/var/run/php5-fpm.sock. So we’ll have to tell the webserver to pass the PHP requests to it.

You could also use a regular UDP socket if you want: change listen in /etc/php5/fpm/pool.d/www.conf to On some operating systems (e.g. FreeBSD), PHP-FPM listens on this UDP socket by default.


Now we need to configure Caddy so it will use PHP-FPM. We also need to specify virtual hosts for the domain(s) we will be using.

The following Caddyfile contains everything you need to run WordPress with PHP-FPM on HTTP/2. {
} {
    root wordpress
    tls server.crt server.key
    log access.log
    # PHP-FPM with Unix socket
    fastcgi / /var/run/php5-fpm.sock php
    # PHP-FPM with regular udp socket
    # fastcgi / php

Caddy will use the wordpress folder as document root, and will pass all PHP requests to a FastCGI process (which is the PHP-FPM process).

The Caddy documentation contains more detailed information on the available directives. Checkout my other blogposts if you need help Running Caddy Server as a service or Creating a self-signed certificate.


Now it’s time to install WordPress. Simple download WordPress and copy the files to the wordpress folder. To install WordPress you can just follow the steps on the screen like any other easy WordPress configuration.

If you want to use HTTP/2, you should configure WordPress with HTTPS enabled. You can do this in Settings, General: change http in the urls to https.
Most browsers only speak HTTP/2 when using TLS. Although TLS only is not marked as mandatory in the RFC 7540, Firefox and Chrome development teams have no actual intents to implement HTTP/2 without TLS.

Creating a self-signed SSL certificate on Linux

The exact commands for generating a self-signed SSL certificate on Linux is something I always forget, so here they are:

Generating a private key

First you need to generate a private key. This private key will be the only key that can decrypt your SSL traffic.

$ openssl genrsa -des3 -passout pass:x -out server.pass.key 2048
$ openssl rsa -passin pass:x -in server.pass.key -out server.key
$ rm server.pass.key

Generating a CSR (Certificate Signing Request)

Using the private key you’ve generated seconds ago, you must now create a CSR (Certificate Signing Request). In most cases you can just use the default values for everything except the common name. The common name is usually the domain of your website.

$ openssl req -new -key server.key -out server.csr

Signing the certificate

Normally you would pass the CSR to a CA (Certificate Authority) who would sign it for you. But using the following command you sign the certificate yourself.

$ openssl x509 -req -days 365 -in server.csr -signkey server.key -out server.crt

Running Caddy Server as a service

Recently I discovered a very promising webserver (written in Go) called Caddy.

Now, Caddy is just an executable, which I wanted to turn into a service on my Ubuntu server.


Running any executable as a service can be done using Upstart. Once you’ve created a config file in /etc/init/my_service.conf, you can use some simple commands like service my_service start, service my_service stop, … and the service will run at boot time.

The output of the program will be logged to /var/log/upstart/my_service.log.

Caddy executable

To allow a non-root user to listen on port 80, you must allow the executable to do so:

$ sudo setcap cap_net_bind_service=+ep ./caddy

Config file

My configuration file looks like this:

description "Caddy Server startup script"
author "Mathias Beke"

start on runlevel [2345]
stop on runlevel [016]

setuid some-caddy-user
setgid some-caddy-group

respawn limit 10 5

    cd /home/mathias/
    exec ./caddy
end script

Explanation of the commands:

  • start on runlevel [2245] specifies the job needs to be started after the basic facilities are up.
  • stop on runlevel [016] is used for a normal shutdown.
  • setuid and setgid can be used to run the job under a specific user account. Set this to an account that is less privileged than the root user. You don’t want to run a webserver with root access!
  • respawn will automatically restart (well… ‘respawn’) the process when it stops for any reason.
  • respawn limit COUNT INTERVAL | unlimited specifies a limit for the automatic respawn of the process.

    Respawning is subject to a limit. If the job is respawned more than COUNT times in INTERVAL seconds, it will be considered to be having deeper problems and will be stopped. Default COUNT is 10. Default INTERVAL is 5 seconds.

    To have the job respawn indefinitely, specify an argument of “unlimited”. However, care should be taken using this option: does your service really stop that frequently? Should it?

     Upstart Cookbook

  • exec executes the actual command.

Swift/iOS: Moving objects with device motion (tilt screen)

One of the cool things of games on smartphones, is that you can control objects using the device motion. But how do you move an object using device tilt (using Swift 2)?

To do so you need to use the CMMotionManager (which is part of Apple’s CoreMotion framework). So don’t forget to include the framework at the top of your code: import CoreMotion.

You must also create one (single) CMMotionManager instance.

let motionManager: CMMotionManager = CMMotionManager()

And start the motion manager in the didMoveToView() function:


Once the motion manager is up and running, we can retrieve motion data from it using the accelerometerData member.

// Get node of object to move
let paddle = childNodeWithName(PaddleCategoryName) as! SKSpriteNode

// Get MotionManager data
if let data = motionManager.accelerometerData {
    // Only get use data if it is "tilt enough"
    if (fabs(data.acceleration.x) > 0.2) {
        // Apply force to the moving object
        paddle.physicsBody!.applyForce(CGVectorMake(40.0 * CGFloat(data.acceleration.x), 0))

If you want to actually move the object, you need to make sure that the object has some physical properties:

// Rectangular physics body around the object
paddle.physicsBody = SKPhysicsBody(rectangleOfSize: paddle.frame.size)
// Make it dynamic
paddle.physicsBody!.dynamic = true
// We don't want the object to fall of the screen
paddle.physicsBody!.affectedByGravity = false
// Add some mass to it
paddle.physicsBody!.mass = 0.02

The data.acceleration member is a struct of type CMAcceleration which contains the acceleration along the x-, y- and z-axis.

struct CMAcceleration {
    var x: Double
    var y: Double
    var z: Double

The following image (source) explains the orientation of those axes.

CoreMotion CMAcceleration axes

Atelier Vidéo Virton 1 2015: Les maffiantômes de Virton

Naar jaarlijkse gewoonte ben ik weer een maand op taalkamp geweest als monitor. Zie hier het resultaat van een workshop ‘Vidéo’ na 12 dagen Roeland kamp in Virton.

Comme d’habitude j’ai fait un mois de camp de langue. Voila le résultat de 12 jours à Roeland. Un atelier Vidéo réalisé par 11 jeunes à Virton.