powershell powershell-3.0 powershell-ise

PowerShell Version check prior to script execution

I'm just asking the communitty if they have come across a way to have the a script check what version of POSH is running prior to the execution of the script. Currently, my work around is the following code:

    #region Final Checks

    #//Check to make sure that version of PowerShell is at least 3.0 before preceding.

    If($PSVersionTable.PSVersion.Major -le 2) {
        Throw "This script has not been tested with version 2.0 or older of PowerShell.  Please execute this script from a system that has PowerShell 3.0 or newer installed.  Windows 8/Server 2012 and newer has it installed by default.  Windows 7/Server 2008 R2 can be patched to have 3.0 installed."
        }

    #endregion Final Checks

I have this right after defining my parameters. However, for my own crazy sake, I want the script to preform this check automatically prior to getting into the meat and potato of the script. A good comparison is using Validate[X] for a parameter. If an operator tries to provide data that doesn't fit my user, an error is thrown prior to the execution of the script. Any ideas? I know that there is nothing in [CmdletBinding()] that does it. Thanks!

Solution

You can use #Requires at the top of your script as a way of telling PowerShell what your script needs to do it's thing.

In your specific case you would put

#Requires -Version 3

This will tell PowerShell that at least PowerShell Version 3 is needed, if someone tries to run the script with PowerShell Version 2 they will receive the following message:

The script 'version3.ps1' cannot be run because it contained a "#requires" statement at line 1 for Windows PowerShell version 3.0. The version required by the script does not match the currently running version of Windows PowerShell version 2 .0. At line:1 char:2 + & <<<< C:\Users\testuser\Desktop\version3.ps1 + CategoryInfo : ResourceUnavailable: (version3.ps1:String) [], ScriptRequiresException + FullyQualifiedErrorId : ScriptRequiresUnmatchedPSVersion

In addition to Version you can require other things as well, all of which are listed in about_Requires on TechNet: https://technet.microsoft.com/en-us/library/hh847765.aspx

#Requires -Version 4
#Requires -Module MyCmdlets

Write-Host "If you see this, you are running Version 4 and have the MyCmdlets Module available"