Styjun

Wikipedia says that PowerShell 2.0 was distributed with Windows 7; so as I use Windows 7, I'm obviously using that version.

But that raises two questions:

1. Why is PowerShell's folder C:WindowsSystem32WindowsPowerShellv1.0 with that trailing v1.0 when it actually should be v2.0?


2. Why is the PowerShell script extension .ps1? Will that extension increment when the version changes?

This is simply the result of a choice made by the Powershell team. They decided to keep both the 1.0 directory and the .ps1 extension for V2 of powershell.

The best way to actually check the version of Powershell is to use the expression $PSVersionTable.PSVersion

C:Usersjaredpar> $PSVersionTable.PSVersion

Major Minor Build Revision
----- ----- ----- --------
2 0 -1 -1

This is an ancient blog post (2007), but it still applies; in short:

• 
  

  As long as new PowerShell versions remain backward-compatible, they will replace earlier versions:

  
  
  

  • The installation location, reflected in $PSHOME - $env:systemrootSystem32WindowsPowerShellv1.0 - will remain the same.

  
  

  • The filename extension - .ps1 - will remain the same.

  
  



• Scripts created for an earlier version will continue to run.




• To mark a script as requiring version <n> at a minimum , use #requires -version <n> at the top of the script (technically, it can be placed anywhere in the script, but it makes sense sense to place it at the top).

In Windows PowerShell, backward compatibility has been maintained since v1 (current is v5.1 as of this writing - likely the last major version; see below), so both the installation location and the filename extension have remained the same.

However, all future effort will go toward the separate, cross-platform PowerShell Core edition, which - as of v6.2.0 - is largely backward-compatible with Windows PowerShell, though its use of .NET Core as the foundation means that certain Windows-specific technologies are fundamentally unavailable - see this blog post.

To get the current session's PowerShell version:

PS> [string] $PSVersionTable.PSVersion
5.1.14393.693 # PSv5.1 example

More generally, hashtable $PSVersionTable, introduced in v2, contains several pieces of version information, (incompletely) described in Get-Help about_Automatic_Variables; WinPS below refers to Windows PowerShell, whereas PSCore refers to PowerShell Core:

Shared properties:

Name Value 
---- ----- 
PSVersion 5.1.14393.693 # The PowerShell version. 
PSEdition Desktop # 'Desktop'=WinPS; 'Core'=PSCore
PSCompatibleVersions 1.0, 2.0, 3.0, 4.0... # array of compatible versions 
WSManStackVersion 3.0 # WS-Management (WinRM) version 
PSRemotingProtocolVersion 2.3 # remoting-protocol version 
SerializationVersion 1.1.0.1 # serialization-protocol version 

Additional properties exclusive to WinPS:

BuildVersion 10.0.14393.693 # ?? Highest supported OS major.minor version, seemingly followed by the build.revision PS version.
CLRVersion 4.0.30319.42000 # The .NET Framework CLR version 

Additional properties exclusive to PSCore:

GitCommitId 6.2.0 # The Git commit ID reflecting an RTM tag (e.g., 6.2.0), release tag (e.g., 6.2.0-rc.1) or a specific non-release commit (e.g., 6.2.0-preview.4-108-g5d54f1aa3871a826409496437e25856dc263ccc4)
OS Microsoft Windows 10.0.17134 # [System.Runtime.InteropServices.RuntimeInformation]::OSDescription
Platform Win32NT # [System.Environment]::OSVersion.Platform