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 debuted with Windows 7 and is a powerful automated task framework that includes over 130 general command-line tools. Combining a scripting language and command-line shell, it’s a service created by Microsoft to allow IT administrators to carry out tasks on Windows machines either remotely or locally.
The tech giant’s command-line interfaces (CLIs), which are a PowerShell predecessor, are far simpler in terms of functionality. Before PowerShell, a number of CLIs performed a similar purpose, with these origins going as far back as command.com, which was the MS-DOS interpreter and the shell in Windows 9x systems. CMD.exe took command.com’s place in Windows NT, stuffing this service with features like command-line completion, access to the command history, and more accurate error messages.
PowerShell's origins can be traced back to 2002, in a project known as the Microsoft Shell (aka Monad), but it took until 2006 for the firm to change its name and bundle it with Windows 7. Since then, PowerShell has been essential to the Windows ecosystem.
While PowerShell and CMD.exe can be utilised on the same system, the latter’s purpose has begun to fade over time. As of November 2017, the default command shell is PowerShell, not CMD.exe, and users can access it directly through File Explorer.
So why the shift to PowerShell?
The limitations in CMD.exe can fundamentally explain the reasons for this shift. Although this service can be used to carry out basic administrative commands on a device, it can’t manage 400 machines at once, or remotely manage certain computing elements like cloud virtual servers.
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?
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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