Saturday, 21 October 2017

X11 Subsystem running WSL Windows 10 subsystem for Linux

This article will look at running graphical Linux applications in Windows 10. As many of you know, Windows 10 can offer a subsystem for Linux running inside Windows 10. We need to download and install a X11 server to be able to run graphical applications that need more than the console, that is a graphical user interface. First off, download XMing for Windows Server from here:

XMing X Server for Windows Server
After installation of Xming, start Xming from your start button.
Now we need to install the Linux Subsystem itself, if you have not done this yet.
Inside Powershell, enter the following command as an administrator:

Enable-WindowsOptionalFeature -Online -FeatureName Microsoft-Windows-Subsystem-Linux 

If you are not a Windows Insider yet, you must join this program. See this page for a description how to obtain WSL or Windows Subsystem for Linux and install it.
Installation guide of WSL - Windows Subsystem for Linux After you have downloaded WSL and installed it using Powershell, select Launch and in the console Window after WSL is further installed and setup, enter a user in Linux you will use as administrator (in Linux terms, this is the root user). You can add another user using the adduser command as root in the Bash console. You can access WSL Linux inside Windows 10 by selecting the menu item Bash on Ubuntu on Windows.

Getting started using WSL

You probably want to update your WSL to the latest version. WSL is a specialized Ubuntu Linux distribiton. Enter the following command to upgrade Linux Kernel and applications, note that it will take time to download package and upgrade to latest versions:

apt-get update && apt-get upgrade The version of Linux distro can be found using this command:

lsb_release -irc 

As we see, I am running Ubuntu 16 Xenial. Next off, we are going to support X-Server. Download first the X11 apps.
root@tore# apt-cache search x11-apps x11-apps - X applications
Install X11-Apps. This will also download all required additional pacages. apt-get install X11-Apps
You need to do this as root or switching to a super user and use the sudo command. Next off, edit your ~/.bashrc file. This is similar to the $Profile file that Powershell uses. You are setting up your environment here to make sure you can use X-Server based Graphical User Interfaces. Such as Gimp, Firefox, Stellarium, Quake and so on - requiring a GUI. But we will start off with running a X11-app, such as Xeyes. Make sure your ~/.bashrc file got the following content. First download Nano if you do not want to use Vim or Vi. (apt-get install nano)
nano ~/.bashrc Next off, add the following line at least: export DISPLAY=:0 We can also add more nice colors and some additional information and offer to switch to a non-root user initally.
export DISPLAY=:0
export LS_COLORS
PS1='\e[37;1m\u@\e[35m\W\e[0m\$ '
echo "Welcome to Bash on Ubuntu on Windows. To switch to your user Tore :"
echo "su tore && cd /home/tore"
echo "Do this now? [y/n]"

read -rsn1 input
if [ "$input" = "y" ]; then
    cd /home/tore
    su tore
    ls -al

echo "To adjust profile file edit the file ~\.bashrc with Nano"

Last, we can test out everything, running Xeyes. Note that you can test out more advanced Linux applications such as Gimp by running: apt-get install gimp This will install Gimp, the Gnu Image Manipulation Program. Then just enter gimp from the console. You can also run such programs in the background by adding the ampersand (&): gimp &

Sometimes, we need to force an exit of such a Linux app with a GUI running from the console entering Ctrl+C to force exit the process.

Monday, 2 October 2017

Setting up a Git alias with a shell function

This short article will show you how to search in the log of a Git repository with a shell function. This shell function can also receive a positional parameter to use in the shell function. First off, edit the .gitconfig file in your user's home folder. On Linux Mint for example, the folder should reside in the /home directory. You can use nano for example. (apt-get install nano)

.gitconfig : 

        searchlog = "!f() { git log --all --decorate --graph -i --grep \"$1\";  }; f"

Note the positonal parameter $1 here, we escape the quote also. The function inside the alias is a shell function.

To use this alias command, type for example:
git searchlog test
This will search the Git log for the parameter passed in (test) and include some flags to decorate the log displayed. Using Git aliases, we can do lenghty Git commands with shorter aliased commands.

Friday, 22 September 2017

Displaying altitude with Google Maps

We will look at displaying additional positional information with Google Maps in this article, such as altitude. First off, we need to add a new object to Google Maps Api v3 - the MarkerWithLabel object. This allows us to add text labels to Google Maps. They are also draggable. I have updated a Plunk below so you can see the end result yourself:

Location in Google Maps with altitude - Plunk

The MarkerWithLabel.js contains the additional javascript code to add the MarkerWithLabel object. We add the marker inside the showPosition method with the following code:

  function showPosition(position){
         var mapCanvas = document.getElementById("demo");
  var myCenter = new google.maps.LatLng(position.coords.latitude, position.coords.longitude); 
  var mapOptions = {center: myCenter, zoom: 12};
  var map = new google.maps.Map(mapCanvas,mapOptions);
  var marker = new google.maps.Marker({
    position: myCenter,
    animation: google.maps.Animation.BOUNCE
   var image = '';

     var altitudeMarker = new MarkerWithLabel({
       position: myCenter,
       draggable: true,
       raiseOnDrag: true,
       icon: image,
       map: map,
       labelContent: position.coords.altitude.toString(),
       labelClass: "labels", // the CSS class for the label
       labelStyle: {opacity: 0.75}

We add the altitude, using the position.coords.altitude object.

A good tip here is to add high accuracy of the GeoLocation.

  function getLocation() {

    var geo_options = {
     enableHighAccuracy: true, 
     maximumAge        : 30000, 
     timeout           : 27000

         if (navigator.geolocation){
          var position = navigator.geolocation.getCurrentPosition(showPosition, null, geo_options);

Note that the client has got to have a positioning device supporting returning the altitude. Most smartphones today got GPS for example.
As a test - you can change the value displayed to position.coords.accuracy.toString() instead. Accuracy is always return in the Coords object.