Prateek Singh - Learn Windows Subsystem for Linux: A Practical Guide for Developers and IT Professionals

Windows Subsystem for Linux (WSL) is not the first subsystem that has ever existed in the Windows operating system; instead, it is a more refined product of years of research in developing isolated subsystems for application sandboxing that are decoupled from the host operating system.

Before we deep dive into setup, configuration, and workings of Windows Subsystem for Linux, lets first look into how it all started and then quickly go through some keywords and definitions that will bring us on the same page and help us across the chapters in this book.

This chapters WSL primer will certainly help, but feel free to skip it for now if you want to get straight into the setup and hands-on workings.

Since the initial releases of Microsoft Windows NT, the operating system was designed to allow coexistence of one or more subsystems within the operating system which were independent of implementation inside the kernel. This allowed us to run Windows 32-bit applications on Windows 64-bit operating systems in the Win32 subsystem and support other subsystems like POSIX and OS/2.

These subsystems were accessible through the API they offered to the applications running on them, and when the application made a call to the API, it was translated to an appropriate Windows NT system call to facilitate the action requested. But, over time, these initial subsystems were retired, and research was led to develop and expand the capabilities of the Windows Subsystem for Linux.

Initial concepts that led to the Windows Subsystem for Linux originated from a project called Project Astoria, a Universal Windows Platform Bridge toolkit that would have allowed developers to build Windows apps for phones by reusing their Android code or run native Android applications on Windows. This was made possible by allowing Android apps to run in an emulated environment with minimal changes and access to Microsoft platform APIs. But, on February 25, 2016, Microsoft made an official announcement that Project Astoria would be discontinued and an argument was given that such an emulator was ultimately redundant to the native, Objective-C toolchain. Later on, insight and research from Project Astoria and another research project known as Project Drawbridge (both outlined later in the chapter) was developed into a compatibility service called Windows Subsystem for Linux version 1. Microsoft released the initial version for the Windows Subsystem for Linux, which is also known as WSL1 in the same year 2016.