How to run Linux binaries natively in Windows 10

Before you get to tinker with cowsay messages in your terminal, there are some basics that need to be sorted out. Firstly, enable Developer Mode by going to Settings > Update and Security > For Developers. If this is the first time Developer Mode is being turned on, you might have to wait for sometime for the feature to get activated. Then, in the Cortana search box, search for Turn Windows Features on or off (you might require Admin priveleges for this), scroll down and check the box against Windows Subsystem for Linux. You might be prompted to restart the computer for the changes to take effect. 

Type bash in the Cortana search box to open a Command Prompt window so that you can install Ubuntu. The installation process is a little different based on the Windows version you have. For versions prior to 1709 (Fall Creators Update), you can simply press Y at the prompt to download the standard Ubuntu distribution (remember WSL is still Beta in Windows 10 versions prior to 1709). In the Fall Creators Update you have more distro options to choose from. You can go to the Microsoft Store and install Ubuntu, openSUSE Leap 42, or SUSE Linux Enterprise Server 42. While these three distros are available readily for integrating with WSL, there are hacks to get the distro of your choice to work with WSL. Either way, select your preferred distro and install from the Store. For this tutorial, we will stick with Ubuntu. The version that is installed is Ubuntu 16.04 LTS.

Once you have installed Ubuntu, you will be asked to create a default UNIX user account. This will be the account that Ubuntu will login to by default. Of course, you can create multiple user accounts as well or use root all the way. Enter a username and password (twice) to create the default user account. This will be the account from which you can run sudo commands. There is also a root account that allows full system access but it is not recommended for regular use due to security concerns. Certain installations will login as root by default. In that case, you can manually add a normal user by typing adduser <username>. The root account can be identified by the # prompt while the $ prompt implies a normal user account.

After creating the default account, it helps to check for updates to the existing installation. Type sudo apt-get update in the bash prompt to update the list of available packages followed by sudo apt-get upgrade to actually install the updated packages. This might take a while so be patient till it finishes. If you skip this step, you might have trouble in connecting to Ubuntu repositories to download additional software. It is also a good idea to periodically check for package updates using the above commands. You can also do a sudo apt-get dist-upgrade to update the kernel, although, it is not very critical.

Now that you have installed Ubuntu and updated its packages, feel free to try out various Bash commands such as ls (for listing directory contents) or pwd (to show the present working directory). You can also open programs such as Vi — the default text editor for Linux. Type vim at the $ prompt to open the text editor.

TIP: You can also run bash commands from the Run dialog box. For example, to open the Vi editor from Windows, open the Run dialog box and type bash -c "vi". This will open a new Bash console window running the Vi editor.

Also, in traditional Linux fashion, you can mount external directories and work with the files in them. With WSL, you can mount Windows folders in Bash and conversely browse Bash files in Windows. For example, to mount the C drive in Bash, type cd /mnt/c and then type ls to view the list of files in your C:\ drive. One important thing to note here is that files that require Administrator access in Windows cannot be simply accessed by using sudo in Bash. To work with files that require Admin access, open Bash as Administrator similar to how you open the Windows Command Prompt as Administrator.

The best part about working with a command line shell in any OS is scripting. WSL being primarily a developer environment, supports scripting in the Bash shell. While you can create scripts in Windows and mount the directory in Bash to execute them, it makes sense to create the script from within Bash itself as Linux uses different End-of-Line (EOL) characters than Windows. Let us create a sample script in the nano text editor that prints out the message, "Hello World!". At the $ prompt type nano ~/helloworld.sh. This will open the nano editor with the file helloworld.sh created in the home directory (in Linux, the ~ represents the home directory).

Enter the following lines in the nano editor —

#!/bin/bash

#Assigning the output to the STRING variable

STRING="Hello World!"

#Echo prints the variable output on screen

echo $STRING 

Press Ctrl+O to save the text file at the path and filename indicated earlier (/home/username/helloworld.sh) and press Ctrl+X to exit nano.

If you're new to Bash scripting, note that the very first line of any script should start with a shebang (#!). The shebang points the path to the interpreter shell for the rest of the script. If a different shell is being used to run the script, the shebang points to the location of that shell. A # indicates a comment line and is usually included just for reference. Outputs can be assigned to variables, in this case the STRING variable. Echo displays the output of the variable on the screen.

Now that we have created our first script, we need to execute it. As a security measure, Bash does not allow directly executing scripts unless the script is explicitly marked as executable. To mark a script as executable we need to change its attributes. Type chmod +x ~/helloworld.sh to change the attribute of the script to an executable. Finally execute the script by typing ~/helloworld.sh. If the script is located in the same working directory, you can also type ./helloworld.sh.

WSL was originally intended to be a command line-only environment as it focused on integrating the Linux developer tool-chain directly within Windows. However, there are some workarounds to get simple GUI programs running from within Bash. Linux uses an X server to display the desktop environment and draw windows on screen. Since WSL does not ship with an X server, we need to get an X server running within Windows and direct the GUI output over ssh. To do so, download an X server program for Windows — Xming and VcXsrv are good options, although, Xming is somewhat outdated but lightweight. Download either of the setup programs and install. This tutorial uses VcXsrv. Open the program from the Start menu or the desktop. You will notice a tray icon with an X. Now that an X server is installed on Windows, let us try to install a graphical program and see how it works. As an example, let us try gvim — the Vi editor with a GUI. 

At the $ prompt, type sudo apt-get install vim-gtk and enter your password if needed. This will install gvim. After the installation process is completed, the GUI output should be directed to the X server installed earlier. To do so, type export DISPLAY=:0 and press Enter. Now type gvim at the $ prompt and press Enter. Voila! You've successfully executed a Linux GUI program in WSL. 

Note: The export DISPLAY command is valid only for the current session and must be run each time Bash is started. Also, not all GUI programs play nice with this method so your mileage may vary.

Now lets try to take things up a notch further. How about installing Synaptic — Ubuntu's package manager so that you can search and install Linux programs with ease. To install Synaptic, at the $ prompt, type sudo apt-get install synaptic. Accept the prompt and wait till the installation finishes. Type sudo synaptic at the $ prompt to open the Synaptic Package Manager GUI. Let's try and install the Firefox browser from this. Search for firefox in the Synaptic Package Manager in the list of results, tick the firefox checkbox. You will be offered additional packages and dependencies as required. Click on Mark in the dialog box and finally click on Apply in the Synaptic window. The required files will be downloaded and installed. Now just type firefox at the $ prompt and relish the good feeling.