PowerShell vs CMD: Unlocking the Power of Windows

We explore the power of Powershell and why it's a worthy successor to the command line interface

Windows PowerShell, which debuted with Windows 7, is a powerful automated task framework that includes more than 130 general command-line tools. Combining a command-line shell and a scripting language, it’s a service developed by Microsoft that allows IT administrators to perform tasks on Windows machines either locally, or remotely.

Microsoft’s command-line interfaces (CLIs), which are a predecessor of PowerShell, are far less complex and also far less sophisticated in terms of functionality. Many CLIs performed a similar purpose before PowerShell, with these origins stretching as far back as command.com, which was the interpreter for MS-DOS and the shell in Windows 9x systems. CMD.exe took the place of command.com in Windows NT, packaging this service with features like more accurate error messages, command-line completion and access to the command history.

Then, in 2002, the origins of PowerShell began as a project known as the Microsoft Shell (aka Monad), although it wasn’t until 2006 when the firm changed its name and bundled it with Windows 7. PowerShell, since then has been an essential part of the Windows ecosystem. While CMD.exe and PowerShell can be used on the same system, the former’s purpose has begun to fade with time. The default command shell as of November 2017 is PowerShell, not CMD.exe, and users can access this directly from File Explorer.

So why the shift to PowerShell?

The reasons for this shift, fundamentally, lie with the limitations in CMD.exe. While this service can be used to run basic administrative commands on a device, it can’t be used to manage 400 machines at once, nor remotely manage computing elements like virtual servers hosted in the cloud.

CMD.exe was never designed to handle such complex computing tasks, which is where PowerShell can steps in. This platform can capably manage devices on the Azure cloud, and handle the creation and monitoring of virtual machines (VMs), as well as configure cloud storage. 

Jeffrey Snover, the head of the PowerShell project team, designed the tool as the missing link between Microsoft's GUI-based administrative tools and the rich set of application programming interfaces (APIs) that expose the company's .NET framework.

He wanted a single command-line tool to support both developers and administrators. In this sense, PowerShell was one of the first forays into what became DevOps, a practice that promotes collaboration between developers and operations teams.

What can PowerShell do? 

PowerShell offers far more functionality than CMD.exe (pictured)

Unlike CMD.exe, PowerShell is an object-oriented tool. Objects are representations of items like files and directories that have their own properties and actions that you can call upon in the CLI. PowerShell understands everything in Windows as an object but also lets you create your own object types.

PowerShell enables admins to get at these objects using more sophisticated commands than you'll find in CMD.exe. One of the tool's key innovations is its use of commandlets (CMDlets). These are small programmes (as little as a dozen lines of code) that can carry out specific tasks using .NET's APIs. They can execute an object's methods, query and change its attributes, and return objects as their results.

CMDlets come in a simple verb-noun form and enable you to get things done quickly. For example, typing Get-Member gives you information about an object, like its properties or attributes.

Get-Member won't do much on its own, though. You need a pipeline, another thing that wasn't available in CMD.exe. Unix and Linux users have enjoyed pipelines for decades, and it's just one command that PowerShell supports from the Bash shell that's common to those systems.

A pipeline lets you take the output of one command and 'pipe' it to another, which takes it as input. You depict a pipeline using |. Say you want to create an object in PowerShell:

$message = Write-Output 'PowerShell is awesome'

You've just used the Write-Output CMDlet to assign some text to what many languages would call a variable. Except in PowerShell, it's not a variable; it's an object with its own methods and properties. You can list them all by piping the $message object to Get-Member:`$message | Get-Member'

You can pipe lots of CMDlets together to create extensive chains of commands, like a conveyor belt of workers adapting something and passing it on to the next person.

Piping aside, this kind of object-oriented programming will be familiar to developers who work with languages like Python. You can even make the object give up certain information about itself using the object's name, a dot, and the property name. For example: $message.Length returns 21

You can create CMDlets yourself in a variety of languages, including Microsoft's own C#. An alternative approach to creating your own PowerShell programmes is to write scripts, which are collections of PowerShell commands collected together into a file that you can run. Although cmd.exe also allows scripts, PowerShell provides its own interactive scripting environment (PowerShell ISE) with a range of extra features like Intellisense, which gives you context-aware method and property options as you're typing.

There's another thing PowerShell gives you that cmd.exe doesn't: the ability to create modules. These are packages of related scripts and/or CMDlets that call upon each other to help carry out a bigger task. You can share lots of complementary scripts and CMDlets far more easily as a module. Sharing is a big part of the PowerShell story. For example, there's a PowerShell gallery containing thousands of scripts and modules from developers.

PowerShell keeps evolving

In 2016, PowerShell was taken open source as PowerShell Core, and since then it has been ported over to Linux and macOS as an alternative to the common Bash shell. However, if you’re planning on installing PowerShell on something other than Windows, you’re also going to have to lift .NET Core (the open source equivalent to Windows .NET) onto the system too. It’s also important to keep in mind that some functionality won’t transfer over - for example, it won’t support the ISE scripting environment.

PowerShell has been updated and expanded upon over the years since, with new functionality and support for classes (objects that can be used as templates to create other objects), as well as integrations with things like Visual Studio Code - which is available for both the native Windows and open source versions.

So now you know its history and how it works, the question then becomes: Should you use it?

The learning curve might seem steep at first, but it’s actually easier to use than you might think. If you can get past that initial hump, then you’ll find that PowerShell offers some genuinely worthwhile features, even if you don’t use each one of them all the time. After all, it’s better to have a powerful toolbox with a set of tools you rarely use, than relying on a 20-year-old set of pliers.

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