The Windows Subsystem for Linux (WSL) has been hugely popular with developers as it negates the need for installing virtual machines or partitioning the hard drive for Linux installs in order to run Linux tools. WSL was introduced in the client version of Windows 10 starting with the Anniversary Update and it now looks like Microsoft is upholding its promise of bringing WSL goodness to the Server version as well.
Starting with Build 16257, you can now enable WSL in the Windows Server Insider Preview builds. Although Windows Server is stripped out of most of the end-user functionality, WSL enables developers and system administrators to access the one elusive Linux command line tool, which otherwise would require a full blown native or VM installation. Microsoft says that it is enabling WSL on Windows Server for those who would like to run Linux tools as part of their workflow as a matter of convenience.
It should be noted however, that WSL on Windows Server is not a Linux Server variant. It is still the client Linux shell that allows you to run daemons, services and other jobs. It cannot therefore, run the aforementioned tasks as background tasks like how a server can normally do.
WSL has been well received by the developer community. Although the aim of WSL was not to run GUI apps, enterprising developers took it upon themselves to enable full GUI drawing within WSL. With the Creators Update, Microsoft has also made available distros of Ubuntu, SUSE Enterprise Linux and Fedora directly from the Windows Store.
WSL is slated for a Windows Server debut with the next release of the Server operating system.