PowerShell for Windows Admins

May 8, 2013  1:08 PM

AD MoL Chapter 10 MEAP

Posted by: Richard Siddaway
Active Directory, Books, PowerShell 3

Chapter 10 of AD Management in a Month of Lunches is now available.


The chapter covers Fine Grained Password Policies

May 7, 2013  3:21 PM

Scripting Games–new Get-ChildItem parameters

Posted by: Richard Siddaway
PowerShell 3, Scripting Games

One improvement that came with PowerShell v3 is the –File and –Directory parameters on Get-ChildItem

If I run this

Get-ChildItem -Path c:\mydata

I will get a mixture of directories and files

Mode LastWriteTime Length Name
—- ————- —— —-
d—- 19/11/2012 20:19 Delivery
d—- 26/02/2013 19:24 Demo
d—- 05/05/2013 11:26 ScriptingGames 2013
d-r– 07/05/2013 18:17 SkyDrive
d—- 24/01/2013 20:08 Summit NA 2012
-a— 06/05/2013 15:26 1336320 2013May_ErrorHandling.doc

If I add the –Recurse parameter it gets worse – I know I’ve got a lot of files and directories in here.

In PowerShell v2 you could separate the directories and files by using PSISContainer

Get-ChildItem -Path c:\mydata | where {$_.PSIsContainer}
Get-ChildItem -Path c:\mydata | where {!$_.PSIsContainer}

will give you the directories only and files only respectively.

It gets easier in PowerShell v3

Get-ChildItem -Path c:\mydata -Directory
Get-ChildItem -Path c:\mydata –File

simple and obvious when you read it.

if you are using PowerShell v3 don’t forget these parameters

May 7, 2013  3:00 PM

Scripting Games-don’t repeat the work

Posted by: Richard Siddaway
PowerShell, Scripting Games, WMI

There are some good features to this script but what really hurts is the two trips to the server for the Win32_Computersystem class

Foreach ($IP in (Get-Content “C:\IPList.txt”))
$Name = (Get-WMIObject Win32_ComputerSystem -ComputerName $ip).Name
$Mem = [math]::truncate((Get-WMIObject Win32_ComputerSystem -ComputerName $ip).TotalPhysicalMemory / 1MB)
$Ver = (Get-WMIObject Win32_OperatingSystem -ComputerName $ip).Caption
[Array]$Cpus = (Get-WMIObject Win32_Processor -ComputerName $ip)
$CpuCount = $Cpus.Count
$Cores = 0
Foreach ($Socket in $Cpus)
$Cores = $Cores + $Socket.NumberOfCores
“$Name,$Mem,$Ver,$CpuCount,$Cores” | Out-File output.csv -Append
it would be better to do this
$comp = Get-WMIObject Win32_ComputerSystem -ComputerName $ip
$name = $comp.Name
$mem = [math]::truncate($comp.TotalPhysicalMemory / 1MB)

Dropping one round trip on a few servers isn’t that big a deal. dropping it on 3000 servers will make a difference
Always think about how your scripts may need to scale one day

May 7, 2013  2:15 PM

Scripting Games–how not to output data

Posted by: Richard Siddaway
PowerShell, Scripting Games, WMI

I haven’t finished blogging about event 1 yet but this caught my eye.

Things aren’t too bad until we hit the bunch of write-host calls

$wrks = (Get-Content -path C:\IPList.txt)
foreach ($wrk in $wrks)
$osver = Get-WMIObject -class win32_operatingsystem -ComputerName $wrk
$procs = @(Get-WMIObject -class win32_processor -ComputerName $wrk)
$plog=($pcors * 2)
$mem = Get-WMIObject -class win32_physicalmemory -ComputerName $wrk
$memtotal = ($mem | Measure-Object -Property capacity -Sum)
$memgb = $memtotal.sum/1gb
Write-host “*******************************************************”
Write-Host “Machine Name: ” $osver.CSName
Write-Host “OS: “$osver.caption
Write-Host “Service Pack: “$osver.csdversion
Write-Host “Build #: “$osver.version
Write-Host “*********** ”
Write-Host “Memory Installed:”
Write-Host “*********** ”
Write-Host “Memory (GB): $memgb ”
Write-Host “Slots used:” $memtotal.Count
Write-Host “*********** ”
Write-Host “Processor(s) Installed:”
Write-Host “*********** ”
Write-Host “Sockets:” $psok
Write-Host “Cores:” $pcors
Write-Host “Logical Procs:” $plog
Write-Host “*********** ”
Write-Host “Processor Details:”
Write-Host “*********** ”
Write-Host “”

The correct way is to create an object and output that

I’ll be blogging a sample answer when the games are over. for now be aware that write-host is worse than backticks

May 6, 2013  11:53 AM

Scripting Games: event 1–use of robocopy

Posted by: Richard Siddaway
PowerShell, Scripting Games

The object of the exercise in both the beginners and advanced sections of event 1 was to move a set of log files older than a give data to an archive folder.

A number of solutions were presented that used robocopy.

This is a workable solution that meets the lettter of the objective but it doesn’t really meet the spirit of the games.

The Scripting Games is about learning to use PowerShell. Within PowerShell there is a move-item cmdlet.

Robocopy isn’t required. Using non-Powershell tools can often be harder than using PowerShell. In your work, and especially in the games, think very carefully before reaching for a non-PowerShell command

May 6, 2013  9:27 AM

Scripting Games–major dislike #2

Posted by: Richard Siddaway
PowerShell, Scripting Games

I’ve already blogged about incorrect use of backticks. Here is another example of un-necessary use of backticks

$Files= Get-ChildItem `
-Path $Path `
-include $Type `
-Recurse `
-File |
Where-Object {$_.LastWriteTime -lt (get-date).AddDays(-$OlderThan) }

Spreading out one parameter per line like this doesn’t add anything to the script and makes working on the get-childitem cmdlet code harder if you want to change it.

Don’t do this

May 6, 2013  7:53 AM

Scripting games-major dislike

Posted by: Richard Siddaway
PowerShell, Scripting Games

One of the things we were asked to blog about as Scripting Games judges was things we liked and disliked. This code is a major dislike

Get-ChildItem $sourceDirectory | ? {$_.PsISContainer } |
% { $subDirectory = $_ ; Get-ChildItem (“$sourceDirectory\$subDirectory”) -Include *.LOG -Recurse } |
? { $logFile = $_ ; $logFile.LastWriteTime -le $modifiedCutOffDate } |
% { $logFileAndSubDirDictionary.Add($logFile, $subDirectory) }

Two things really make this stand out as how not to do things:

Using % & ? as aliases in a script. They are tolerable (just) in an interactive command but have no place in a script. Tab completion is so easy. Use the proper command.
Putting multiple commands on a line separated by ; It makes the code hard to read and awkward to work out whats going on. It also makes script testing, debug and maintenance much more difficult
Avoid these two things in your scripts

May 6, 2013  4:20 AM

Scripting Games–integer parameters

Posted by: Richard Siddaway
PowerShell, Scripting Games

I keep seeing parameter constructs like this:

[int]$age = ’90′

Why set the parameter to an integer and then set the default as a string. PowerShell will convert but it just doesn’t make sense.

All you need is

[int]$age = 90

May 5, 2013  4:30 PM

Scripting games–using parameters

Posted by: Richard Siddaway
PowerShell, Scripting Games

I am seeing an incredible number of scripts that have this sort of coding round parameters

# Input from the user
[ValidateScript({Test-Path $_ })]
[String]$SourcePath = ‘C:\Application\Log’,

[ValidateScript({Test-Path $_ })]
[String]$ArchivePath = ‘\\NASServer\Archives’,

[Int]$Days = 90

Why do you need to state that Mandatory=$false or that ValueFromPipeline=$False. The DEFAULT values are false. You only need to use them if you are setting them to TRUE.

Its a waste of coding time and processing time when you run the script.

I remember blogging about this last year.

Please stop doing it so I don’t have to blog about it next year

May 5, 2013  5:13 AM

Scripting Games–observation

Posted by: Richard Siddaway
PowerShell, Scripting Games

I don’t have the numbers to back this up but my feeling is that the Scripting Community is marking the entries for this years Games in a harsher manner than the judges did over the last few games.

What will be very interesting is the level, type and usefulness of the comments that come through. if you do mark low please explain why

Whether this relaxes over the next few entries will be interesting to see.

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