Skip to main content

New Syntax for Hash Tables with Select-Object

Wow!  I am actually getting around to blogging this year.  This has been an epic year in terms of how busy I have been.  Between speaking at both the PowerShell Conferences in Europe and Asia, but also expanding my client base in Asia and the Pacific islands, I have been busy.  Oh, let’s not forget adding Windows Server 2016 classes, Security+ and my work on the Azure platform. 

OK, yes I have been busy.  At some point, what I have been learning does get spilled over into my classes and this blog.

One of the sticky points with learning PowerShell has been the creation of calculated properties with Select-Object.  To do so you need to use a hash table, associative table, or dictionary.  What you call it depends on your background.   Just remember that most IT pros who take my PowerShell classes are not programmers and have never been trained as such.  Makes for an interesting week for me.  
Below is an example of how we have been teaching calculated properties.
Get-Process |
    Select-Object -Property Name,
        @{
            Name = 'VirtMemory'
            Expression = {$PSItem.VM}
        }

You could short hand it as such.

Get-Process |
    Select-Object -Property Name, @{N = 'VirtMemory'; E = {$PSItem.VM}}

Well, that hash table is the problem.  I have not found a way to eliminate it, but I have found a way to write it a different way.

$Hash1 = @{ 'Name' = 'VirtMemory'; Expression = {$PSItem.VM}}
Get-Process | Select-Object -Property Name, $Hash1

The idea is to break it up into multiple parts so the student can focus more on what is going on and less on the confusing syntax used with Select-Object. You can add additional calculated properties as shown below.

$Hash1 = @{ 'Name' = 'VirtMemory'; Expression = {$PSItem.VM}}
$Hash2 = @{ 'Name' = 'WorkMemory'; Expression = {$PSItem.WS}}
Get-Process | Select-Object -Property Name, $Hash1, $Hash2

This technique will not work for all.  If what you are using works for you, then continue to use your technique.  I will be introducing this syntax in my PowerShell class next week in Phoenix to gauge the class response to this technique as a step in their understanding of how to perform this very common task and understand it.
 


Comments

Popular posts from this blog

Adding a Comment to a GPO with PowerShell

As I'm writing this article, I'm also writing a customization for a PowerShell course I'm teaching next week in Phoenix.  This customization deals with Group Policy and PowerShell.  For those of you who attend my classes may already know this, but I sit their and try to ask the questions to myself that others may ask as I present the material.  I finished up my customization a few hours ago and then I realized that I did not add in how to put a comment on a GPO.  This is a feature that many Group Policy Administrators may not be aware of. This past summer I attended a presentation at TechEd on Group Policy.  One organization in the crowd had over 5,000 Group Policies.  In an environment like that, the comment section can be priceless.  I always like to write in the comment section why I created the policy so I know its purpose next week after I've completed 50 other tasks and can't remember what I did 5 minutes ago. In the Group Policy module for PowerShell V3, th

Return duplicate values from a collection with PowerShell

If you have a collection of objects and you want to remove any duplicate items, it is fairly simple. # Create a collection with duplicate values $Set1 = 1 , 1 , 2 , 2 , 3 , 4 , 5 , 6 , 7 , 1 , 2   # Remove the duplicate values. $Set1 | Select-Object -Unique 1 2 3 4 5 6 7 What if you want only the duplicate values and nothing else? # Create a collection with duplicate values $Set1 = 1 , 1 , 2 , 2 , 3 , 4 , 5 , 6 , 7 , 1 , 2   #Create a second collection with duplicate values removed. $Set2 = $Set1 | Select-Object -Unique   # Return only the duplicate values. ( Compare-Object -ReferenceObject $Set2 -DifferenceObject $Set1 ) . InputObject | Select-Object – Unique 1 2 This works with objects as well as numbers.  The first command creates a collection with 2 duplicates of both 1 and 2.   The second command creates another collection with the duplicates filtered out.  The Compare-Object cmdlet will first find items that are diffe

How to list all the AD LDS instances on a server

AD LDS allows you to provide directory services to applications that are free of the confines of Active Directory.  To list all the AD LDS instances on a server, follow this procedure: Log into the server in question Open a command prompt. Type dsdbutil and press Enter Type List Instances and press Enter . You will receive a list of the instance name, both the LDAP and SSL port numbers, the location of the database, and its status.