How to use dotNET (.NET) classes and methods in PowerShell

Shruti Sharma — Fri, 10 Jul 2020 08:21:22 +0000

As a beginner in PowerShell, I wanted to explore how to use Microsoft .NET framework class library to run my PowerShell scripts. This information might be helpful if you’re going to use PowerShell at some point.

.NET languages are object-oriented with hierarchies of base and derived classes. A hierarchical namespace organizes classes. This allows you to locate a class in the .NET framework through a fully qualified name. For instance, the fully qualified name of the Process class is System.Diagnostics.Process.

Let us take a look at how this works.

In PowerShell, Get-TimeZone cmdlet gets the current time zone. Its equivalent .NET Framework class provides exactly the same output.

PS /> Get-TimeZone

Id                         : Singapore
DisplayName                : (UTC+08:00) Singapore Standard Time
StandardName               : Singapore Standard Time
DaylightName               : GMT+08:00
BaseUtcOffset              : 08:00:00
SupportsDaylightSavingTime : True

In order to find out the .NET class for the TimeZone, we use Get-Member cmdlet in PowerShell. The Get-Member cmdlet helps to identify what type of object the command returns, and also the properties and methods associated with that cmdlet (as shown below).

PS /> Get-TimeZone | Get-Member


   TypeName: System.TimeZoneInfo

Name                       MemberType Definition
----                       ---------- ----------
Equals                     Method     bool Equals(System.TimeZoneInfo other), bool Equals(System.Object obj), bool IEquatable[TimeZoneI…
GetAdjustmentRules         Method     System.TimeZoneInfo+AdjustmentRule[] GetAdjustmentRules()
GetAmbiguousTimeOffsets    Method     timespan[] GetAmbiguousTimeOffsets(System.DateTimeOffset dateTimeOffset), timespan[] GetAmbiguous…
GetHashCode                Method     int GetHashCode()

Here System.TimeZoneInfo is the .NET class that displays the same output.

PS /> [System.TimeZoneInfo]::local

Id                         : Singapore
DisplayName                : (UTC+08:00) Singapore Standard Time
StandardName               : Singapore Standard Time
DaylightName               : GMT+08:00
BaseUtcOffset              : 08:00:00
SupportsDaylightSavingTime : True

By using the GetType method we can verify that both commands return a System.TimeZoneInfo object. These two commands are shown here.

PS /> (Get-TimeZone).gettype()

IsPublic IsSerial Name                                     BaseType
-------- -------- ----                                     --------
True     True     TimeZoneInfo                             System.Object

PS /> ([System.TimeZoneInfo]::local).GetType()

IsPublic IsSerial Name                                     BaseType
-------- -------- ----                                     --------
True     True     TimeZoneInfo                             System.Object

PS />

As we can see both these commands do exactly the same thing. However, I think PowerShell cmdlet is readable and convenient to use.

It is always a best practice, to use a native Windows PowerShell cmdlet when it exists unless there is a good reason for not doing so.
One such example is using a static method within a .NET class. To determine the power of a number we make use of System.Math class and use the method Pow

PS /> [System.Math]::Pow(4,3)
64
PS /> [System.Math]::
E                 Atan              Ceiling           Exp               Log2              Round             Tanh
PI                Atan2             Clamp             Floor             Max               ScaleB            Truncate
Abs               Atanh             CopySign          FusedMultiplyAdd  MaxMagnitude      Sign
Acos              BigMul            Cos               IEEERemainder     Min               Sin
Acosh             BitDecrement      Cosh              ILogB             MinMagnitude      Sinh
Asin              BitIncrement      DivRem            Log               Pow               Sqrt
Asinh             Cbrt              Equals            Log10             ReferenceEquals   Tan

In this case, we are calling the .net framework static method of a class to do something that we couldn't do in PowerShell natively. Although, we could write a function in PowerShell, that uses this approach.

Features Of PowerShell

Shruti Sharma — Fri, 03 Jul 2020 12:48:59 +0000

PowerShell is open-source – PowerShell code base is published on GitHub and open to community contributions “https://github.com/PowerShell/PowerShell”
Cmdlets − Compiled commands in PowerShell are called cmdlets. Cmdlets perform common system administration tasks, for example managing the registry, services, processes, event logs, and using Windows Management Instrumentation (WMI).
Object-Based Approach − PowerShell is an object-oriented scripting language. PowerShell possesses powerful object manipulation capabilities. Objects can be sent to other tools or databases directly.
PowerShell design goals - PowerShell is designed to improve the command-line and scripting environment by eliminating long-standing challenges and adding new and modern features like discoverability, consistency, etc.
Task-oriented − PowerShell is a cross-platform task automation and configuration management framework and provides supports for existing scripts and command-line tools.
Getting into the Pipeline - PowerShell pipes objects, not text, between commands. Each object passed along a pipeline has the methods and properties common to that type of object. PowerShell’s pipeline implementation is much richer and more modern.
Simple to Use − Simplified, command-based navigation lets users navigate the registry and other data stores similar to the file system navigation. As cmdlets and system data stores use common syntax and have common naming conventions, data sharing is easy.
Discoverability - Powershell has been designed to be user friendly and allow users to easily discover new features and get help. For this purpose, the two most important cmdlets in PowerShell are Get-Help and Get-Command.
Extensible interface − PowerShell is customizable as independent software vendors and enterprise developers can build custom tools and utilities using PowerShell to administer their software.
Easy transition to scripting - PowerShell's command discoverability makes it easy to transition from typing commands interactively to creating and running scripts.

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How to use dotNET (.NET) classes and methods in PowerShell

Features Of PowerShell