Why is PowerShell Used?
PowerShell is a task automation system that consists of a command-line shell, a scripting language, and a configuration management framework that works across platforms. PowerShell is compatible with Windows, Linux, and macOS.
Microsoft’s PowerShell is a task automation and configuration management framework that includes a command-line shell and a scripting language. It was originally a Windows-only component known as Windows PowerShell, but with the launch of PowerShell Core on August 18, 2016, it became open-source and cross-platform. The former uses the.NET Framework, while the later uses.NET Core.
Administrative activities in PowerShell are often accomplished through cmdlets (pronounced command-lets), which are specialized.NET classes that implement a certain action. These work by allowing PowerShell to access data from various data stores, such as the file system or registry, that have been made available to it via providers.
PowerShell allows third-party developers to contribute cmdlets and providers. Scripts can use cmdlets, which can then be bundled as modules.
PowerShell also has a hosting API that allows the PowerShell runtime to be integrated into other programs. The PowerShell capability in these programs can then be used to implement various actions, including those provided via the graphical interface.
Microsoft Exchange Server 2007 took advantage of this feature to expose its administration capabilities as PowerShell cmdlets and providers, and to develop graphical management tools as PowerShell hosts that run the required cmdlets. Other Microsoft products, such as Microsoft SQL Server 2008, provide management interfaces that may be accessed via PowerShell cmdlets.
The Get-Help cmdlet provides access to PowerShell’s extensive console-based help (equivalent to man pages in Unix shells). The Update-Help cmdlet can retrieve updated local help content from the Internet. Alternatively, the -online switch to Get-Help can be used to get help from the web on a case-by-case basis.
Background
MS-DOS was the only operating system that used a command line interface.
A few fundamental internal instructions are supported by both. A separate console program must be built for other purposes. They also come with a simple scripting language (batch files) that may be used to automate a variety of operations.
The problem improved in Windows Server 2003, but scripting support remained inadequate.
PowerShell
Microsoft rebranded Monad Windows PowerShell on April 25, 2006, not long after the initial introduction, portraying it as an important part of its management technology portfolio. At the same time, PowerShell Release Candidate 1 was released.
The fact that this was now a part of Windows, rather than just an add-on, was an important aspect of both the name change and the RC.
On January 30, 2007, PowerShell for previous versions of Windows was released. PowerShell v2.0 was started before PowerShell v1.0 was released.
Microsoft released three community technology previews during the development process (CTP). These releases were made available to the general public by Microsoft.
Windows 10 includes a PowerShell testing framework. And it was stated by the Microsoft itself on August 18, 2016, that PowerShell would be open-source and cross-platform, which will now include the support for Windows, macOS, CentOS, and Ubuntu.
On GitHub, the source code was made public. Because of the shift to open source, a new version of PowerShell called “PowerShell Core” was produced, which runs on.NET Core. It’s not to be confused with “Windows PowerShell,” which uses the entire.NET Framework. PowerShell Core is included with Windows Server 2016 Nano Server starting with version 5.1.
Scripting language
In simple words we can say that the PowerShell is a scripting language that is often used to automate system management which means that it gives the user the facility to run things automatically , instead of being manually run by a user. It’s also utilized in CI/CD systems to develop, test, and deploy solutions. The.NET Common Language Runtime underpins PowerShell (CLR).
In PowerShell there is no need of parse text output in order to get the information. In PowerShell the .NET objects are used for all inputs and outputs. The following are some of the characteristics of the PowerShell scripting language:
- The PowerShell is a scripting language has Extensible formatting systemfor easy output.
- The PowerShell is a scripting language is Extensible through functions, classes, scripts, and modules
- The PowerShell is a scripting language has Built-in support for common data formats like CSV, JSON, and XMLs
- The PowerShell is a scripting language has Extensible type systemfor creating dynamic types.
Configuration management
Desired State Configuration (DSC) in PowerShell is a management framework that allows you to manage your company infrastructure using configuration as code. You can do the following with DSC:
- For repeatable deployments, create declarative configurations and custom scripts.
- Ensure that configuration settings are enforced and that configuration drift is reported.
- Use push or pull models to deploy configuration.
What is a PowerShell command (cmdlet)?
PowerShell commands are referred to as cmdlets which are pronounced as command-lets. PowerShell also allows you to perform any command on your system in addition to cmdlets.
What is a cmdlet?
PowerShell cmdlets are not standalone executables, but rather native PowerShell commands. PowerShell modules are collections of cmdlets that can be loaded on demand.
In the PowerShell environment, cmdlets are specialized commands that perform certain tasks. These are the PowerShell stack’s native commands. Cmdlets, such as Get-ChildItem, have a Verb-Noun naming pattern, which makes them self-documenting code.
If a cmdlet returns a collection of objects, each object in the collection is handled before moving on to the next object in the pipeline.
Cmdlets are specialized.NET classes that the PowerShell runtime creates and calls throughout the execution process.
These foundation classes define a set of methods. – BeginProcessing(), ProcessRecord() and EndProcessing() – which is overridden by the cmdlet’s implementation to give the capabilities When a cmdlet is invoked, PowerShell calls these functions in order, with ProcessRecord() being called if pipeline input is received.
An enumeration of common verbs is presented.
If a cmdlet accepts pipeline or command-line parameter input, the class must have a mutator implementation for the appropriate property.
PowerShell calls the mutator with the parameter value or pipeline input, which is recorded in class variables by the mutator implementation. The methods that implement the functionality then refer to these values.
They can be written in any.NET language and can reference any.NET API. Furthermore, PowerShell provides APIs such as WriteObject(), which can be used to access PowerShell-specific features like writing resultant objects to the pipeline.
Cmdlets can directly use.NET data access APIs or leverage the PowerShell framework of PowerShell Providers, which make data stores available via unique paths. Drive letters and hierarchies within them, referred to as directories, are used to expose data stores.
Other programs can register cmdlets with PowerShell so that it can handle them, and they can also add specialized providers if they encapsulate any datastore (such as a database).
Cmdlet names
PowerShell names cmdlets with a Verb-Noun name pair. The Get-Command cmdlet in PowerShell, is used to retrieve all of the cmdlets that are registered in the command shell. Here the noun that is present in the command specifies the resource on which the cmdlet performs its action, whereas the verb that is present in the command identifies the action that the cmdlet does.