Powershell – Check for PS version and act accordingly…

In recent posts, we’ve been outlining some important day-to-day differences in PowerShell CMDlets and features between v2 and v3.  And right now I’m working with a customer that is in the midst of transitioning between XP and Win7, and between Server 2003 and 2008/2012, where these differences really start to matter performance-wise. 

So, we’ve got lots of PowerShell tools we wrote in v2 that we are slowly getting around to updating to the new features in v3.  But the thing is, we still can’t be certain where these scripts will be run, and by whom.  So we’ve put together a little “version detector” to help run the correct version of the command and give the best performance possible, whenever possible.  And as a result, you — the reader — can apply this type of thing to any script that might be run in a mixed environment.

This example below features the new -Directory flag in the PowerShell v3 Get-ChildItem, though you could just as easily replace that line in each section with any other CMDlet that behaves differently between versions.  Just modify this section, and wrap it around your CMDlet with the updated v3 capability…

 

$hostVersionInfo = (get-host).Version.Major
if ( $hostVersionInfo -eq "2" )
{
  # For PowerShell v2
  write "We appear to be using PS version $hostVersionInfo... That's okay, but this script processes faster with PS v3!"
  write ""
  $containers = Get-ChildItem -path $MoLoPath$CurrentParent -recurse | ? {$_.psIscontainer -eq $true}
}
elseif ( $hostVersionInfo -eq "3" )
{
  # For PowerShell v3
  write "We appear to be using PS version $hostVersionInfo... Good!"
  write ""
  $containers = Get-ChildItem -Directory -path $MoLoPath -recurse
}
else
{ 
  write-host "Unknown/unapproved version of PowerShell. Exiting!"
  exit
}

 

Normally, I’d explain some of the functionality in the script; but it’s fairly simple, well-commented, and in general pretty descriptive.  It just detects which version of PowerShell you’re running, and runs one of the two version of the CMDlet.  So you should be able to figure it out quickly even if you’re new to this stuff. 

Of course, if you have a question (or have a better way of getting it done), feel free to comment. 

So that’s it, I hope it helps!

🙂

 

 

2013-05-22T22:29:39+00:00 May 22nd, 2013|Uncategorized|

About the Author:

Jeremy is just a regular guy that likes to occasionally tell the world about stuff.