Enterprise Admins.org

Earlier in the week I had the privilege of presenting an introduction to Powershell/PowerCLI webex to a group of VMware customers. To help explain the Where-Object, Select-Object, and Sort-Object cmdlets, I thought it would be helpful to create a Get-Beer function. This function was a success, so I thought I would share it here. The function is very basic — it uses Import-CSV to read information from a file and returns the results ordered by name. The results can then be piped to other functions for demo purposes.

You can download a sample beer.csv file here.

Here is the function:
[cc lang=”powershell”]
<# .SYNOPSIS List Miller Coors beer .DESCRIPTION This function returns a list of beer bottled by MillerCoors. The object also includes nutrition and alcohol information. .EXAMPLE PS C:\> Get-Beer
.NOTES
This function was created for demo purposes only.
VMware PowerCLI rocks!
#>
Function Get-Beer {
$myResults = @()
Import-Csv C:\tmp\beer.csv | Sort-Object Name | %{
[decimal]$thisAlcoholPercent = $_.”Alcohol%”
[decimal]$thisCaloriesPer12oz = $_.CaloriesPer12oz
$myResults += new-object -type PSObject -Property @{
Name = $_.Name
AlcoholPercent = $thisAlcoholPercent
CaloriesPer12oz = $thisCaloriesPer12oz
Category = $_.Category
} #End New-Object
} #End for each object

# Return a custom PS object containing each beer
return ($myResults | Select-Object Name, AlcoholPercent, CaloriesPer12oz, Category)
} #End Function
[/cc]

The function type casts the numeric values as decimal so that they properly sort. To run this, place a beer.csv file in the C:\tmp path (or adjust the filename/path in the function), paste the function into a powershell window and you are ready to go.

Here are a few examples of what you can do with this function:

Get-Beer

(Get-Beer).count

Get-Beer | Sort-Object AlcoholPercent -Descending | Select-Object Name, AlcoholPercent -First 5

Get-Beer | Where-Object {$_.CaloriesPer12oz -lt 200 -AND $_.Category -eq "Craft"} | Sort-Object AlcoholPercent -Descending | Select-Object -First 5

This is a very simple post, but it shows how to make the Powershell title bar contain useful information. By default the Powershell title contains the path to the powershell.exe file — here is an example:

To make this more useful, I’ve added a line to my powershell profile that looks like this:

$host.ui.rawui.WindowTitle="PowerShell $($psversiontable.psversion) as $($env:username)"

*Note: all this text should appear on the same line in your profile.

This change adds the Powershell version number and running user name to the title bar. This is useful in my environment because I often have the need to run Powershell as a different user. Here is an example of the update:

I placed this in the all users profile located here:

%windir%\system32\WindowsPowerShell\v1.0\profile.ps1 

This profile is machine specific and executes anytime you open a powershell console for any user. While you have the profile open, I have one more time saving suggestion. If you use the Send-MailMessage cmdlet often, add this line:

$PSEmailServer = "smtp-relay.mydomain.local"

With this variable specified, you no longer need the “-SmtpServer” attribute to send a message — this global variable will automatically be used.

Hope this helps!

In most of my Powershell scripts I make use of the PSCustomObject to store results. The example I first learned (and use all the time) looks just like this:

[cc lang=”Powershell”]
$item = “” | Select Name, RAM, CPU
$item.Name = “blah”
$item.Ram = 4096
$item.Cpu = 1
$item
[/cc]

In the above example, you create a blank PSCustomObject on line 1 which has Name, RAM and CPU placehoders. Then on lines 2 through 4 you assign values to each attribute. Finally on line 5 you do something with the variable $item. In the above example, the contents of the $item variable are displayed onscreen. Normally you’d see something like $myreport += $item which stores the new item in a collection called $myreport.

The problem is adding an additional attribute to your object requires two steps — first, you must declare the attribute on line 1 and then assign something to the attribute after it is declared. For example, if I wanted to add PowerState to my report, I would have to add “, PowerState” on the first line. If you forget, which happens to me all the time, you get this error:

$item.PowerState = "PoweredOff"
Property 'PowerState' cannot be found on this object; make sure it exists and is settable.
At line:1 char:7
+ $item. <<<< PowerState = "PoweredOff"
    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException
    + FullyQualifiedErrorId : PropertyAssignmentException

I recently found a new example that I like a lot better. Here is an example:

[cc lang="Powershell"]
$item2 = new-object -type PSObject -Property @{
Name = "blah"
RAM = 4096
CPU = 1
}
$item2
[/cc]

In the above example, attributes are created as needed, removing the need to pre-define them on the first line of the script. This method removes the need to specify "$item." for each attribute, making the code easier to read/maintain/support.

This is a very simple example, but I hope others find it useful.