Defining what a shell is can be a bit tricky, especially at Microsoft, because pretty much everything at Microsoft has something called a shell. Windows Explorer is a shell. Visual Studio has a component called the shell. Heck, even the Xbox has something they call a shell.
Historically, the term shell describes the piece of software that sits over an operating system’s core functionality. This core functionality is known as the operating system kernel (shell…kernel…get it?).
A shell is the piece of software that lets you access the functionality provided by the operating system. Windows Explorer is properly called a shell because it lets you access the functionality of a Windows system. For our purposes, though, we’re more interested in the traditional text-based environment where the user types a command and receives a response. In other words, a shell is a command-line interpreter. The two terms can be used for the most part interchangeably.
What is PowerShell, and why was it created? PowerShell is the new command-line / scripting environment from Microsoft. The overall goal for this project was to provide the best shell scripting environment possible for Microsoft Windows. This statement has two parts, and they’re equally important, because the goal wasn’t just to produce a good generic shell environment but rather to produce one designed specifically for the Windows environment.
Although drawing heavily from existing command-line shell and scripting languages, the PowerShell language and runtime were designed from scratch to be an optimal environment for the modern Windows operating system.
Historically, the Windows command line has been weak. This is mainly the result of Microsoft’s early focus on computing for the average user, who is considered neither particularly technical nor particularly interested in computers. Most of the development effort for Windows was put into improving the graphical environment for the nontechnical user, rather than creating an environment for the computer professional.
Although this was certainly an enormously successful commercial strategy for Microsoft, it has left some segments of the community underserved.
By environmental forces, I mean the various business pressures and practical requirements that needed to be satisfied.
