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about_Windows_Powershell_5.1

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Short description

Describes new features that are included in Windows PowerShell 5.1.

Long description

Windows PowerShell 5.1 includes significant new features that extend its use, improve its usability, and allow you to control and manage Windows-based environments more easily and comprehensively.

Windows PowerShell 5.1 is backward-compatible. Cmdlets, providers, modules, snap-ins, scripts, functions, and profiles that were designed for Windows PowerShell 4.0, Windows PowerShell 3.0, and Windows PowerShell 2.0 generally work in Windows PowerShell 5.1 without changes.

  • New cmdlets: local users and groups; Get-ComputerInfo
  • PowerShellGet improvements include enforcing signed modules, and installing JEA modules
  • PackageManagement added support for Containers, CBS Setup, EXE-based setup, CAB packages
  • Debugging improvements for DSC and PowerShell classes
  • Security enhancements including enforcement of catalog-signed modules coming from the Pull Server and when using PowerShellGet cmdlets
  • Responses to a number of user requests and issues

Windows PowerShell 5.1 is installed by default on Windows Server version 2016 and higher and Windows client version 10 and higher.

To install Windows PowerShell 5.1 on older versions of Windows, see Install and Configure WMF 5.1. Be sure to read the download details, and meet all system requirements, before you install Windows Management Framework 5.1.

You can also read about changes to Windows PowerShell 5.1 in What's New in Windows PowerShell.

PowerShell Editions

Starting with version 5.1, PowerShell is available in different editions which denote varying feature sets and platform compatibility.

  • Desktop Edition: Built on .NET Framework and provides compatibility with scripts and modules targeting versions of PowerShell running on full footprint editions of Windows such as Server Core and Windows Desktop.
  • Core Edition: Built on .NET Core and provides compatibility with scripts and modules targeting versions of PowerShell running on reduced footprint editions of Windows such as Nano Server and Windows IoT.

Learn more about using PowerShell Editions

Catalog Cmdlets

Two new cmdlets have been added in the Microsoft.PowerShell.Security module. These cmdlets generate and validate Windows catalog files.

New-FileCatalog

New-FileCatalog creates a Windows catalog file for set of folders and files. This catalog file contains hashes for all files in specified paths. Users can distribute the set of folders along with corresponding catalog file representing those folders. This information is useful to validate whether any changes have been made to the folders since catalog creation time.

New-FileCatalog [-CatalogFilePath] <string> [[-Path] <string[]>]
 [-CatalogVersion <int>] [-WhatIf] [-Confirm] [<CommonParameters>]

Catalog versions 1 and 2 are supported. Version 1 uses the SHA1 hashing algorithm to create file hashes; version 2 uses SHA256. You should use catalog version 2.

To verify the integrity of catalog file (Pester.cat in above example), sign it using Set-AuthenticodeSignature cmdlet.

Test-FileCatalog

Test-FileCatalog validates the catalog representing a set of folders.

Test-FileCatalog [-Detailed] [-FilesToSkip <String[]>]
 [-CatalogFilePath] <String> [[-Path] <String[]>]
 [-WhatIf] [-Confirm] [<CommonParameters>]

This cmdlet compares all file hashes and their relative paths found in a catalog with files on disk. If it detects any mismatch between file hashes and paths it returns the status as ValidationFailed. Users can retrieve all this information using the Detailed parameter. It also displays signing status of catalog in Signature property, which is equivalent to calling Get-AuthenticodeSignature cmdlet on the catalog file. Users can also skip any file during validation using the FilesToSkip parameter.

Module Analysis Cache

Starting with WMF 5.1, PowerShell provides control over the file that's used to cache data about a module, such as the commands it exports.

By default, this cache is stored in the file ${env:LOCALAPPDATA}\Microsoft\Windows\PowerShell\ModuleAnalysisCache. The cache is typically read at startup while searching for a command and is written on a background thread sometime after a module is imported.

To change the default location of the cache, set the $env:PSModuleAnalysisCachePath environment variable before starting PowerShell. Changes to this environment variable only affect child processes. The value should name a full path (including filename) that PowerShell has permission to create and write files. To disable the file cache, set this value to an invalid location, for example:

$env:PSModuleAnalysisCachePath = 'nul'

This sets the path to an invalid device. If PowerShell can't write to the path, no error is returned, but you can see error reporting using a tracer:

Trace-Command -PSHost -Name Modules -Expression {
  Import-Module Microsoft.PowerShell.Management -Force
}

When writing out the cache, PowerShell checks for modules that no longer exist to avoid an unnecessarily large cache. You can disable the checks using the following setting:

$env:PSDisableModuleAnalysisCacheCleanup = 1

Setting this environment variable takes effect immediately in the current process.

Specifying module version

In WMF 5.1, using module behaves the same way as other module-related constructions in PowerShell. Previously, you had no way to specify a particular module version. If there were multiple versions present, this resulted in an error.

In WMF 5.1:

  • You can use ModuleSpecification Constructor (Hashtable). This hash table has the same format as Get-Module -FullyQualifiedName.

    Example: using module @{ModuleName = 'PSReadLine'; RequiredVersion = '1.1'}

  • If there are multiple versions of the module, PowerShell uses the same resolution logic as Import-Module and doesn't return an error.

Improvements to Pester

In WMF 5.1, the version of Pester that ships with PowerShell has been updated from 3.3.5 to 3.4.0. You can review the changes in versions 3.3.5 to 3.4.0 by inspecting the CHANGELOG in the GitHub repository.

KEYWORDS

What's New in Windows PowerShell 5.1