Bennett Adelson Technical Blog

Bennett Adelson Technical Blog

Powershell – Get started with the low-hanging fruit


Much has been written about PowerShell (PS) cmdlets, whether they be the new ones available in v3, the Quest tools, those built into various products like SQL Server and Citrix XenDesktop, or the PSCX community extensions (to name just a few). These cmdlets are great, but don’t forget that PS is an object-oriented, interpreted scripting language, capable of taking advantage of .NET APIs and COM objects like IE and MS Word. Need to write a utility with a graphical interface so the help desk can easily provision a service for a user? Use the .NET System.Drawing and System.Windows.Forms namespaces. Want to open a web page repeatedly to ‘screen scrape’ it? Create a new object of type ‘InternetExplorer.Application’ and have at it!

Admittedly, there is a learning curve involved here, but here are some PS examples that allow you to use PowerShell quickly you may have overlooked:

1. Use the get-process cmdlet when tracking down the process that is causing performance problems. Combine that with the out-gridview and you can add additional selection criteria, and then select just the processes you want to output:

Get-process | out-gridview –passthru | fl

1a  1b 1c

2. The out-gridview is fine if you have a small amount of data, but you need more automation if you have a large base. Combining the built-in csvde.exe with import-csv lets you scale to larger sizes:

Csvde –f users.csv

2a

$users = import-csv users.csv

$users | where {$_.sAMAccountName.StartsWith(“S”)} | select name

2b

3. Let’s gather CPU, memory, and disk statistics. Let’s write a PS workflow (PSFW, new with v3) that will gather all of the statistics in parallel, then pass it an array of the performance counters provided by perfmon we want to examine:

Workflow gather_stats ($perfmoncounters)
{
    Foreach –parallel ($counter in $perfmoncounters)
   {
      (Get-counter $counter). CounterSamples
    }
}
$arr_perfmoncounters = ‘\Processor(_Total)\% Processor Time’, `
      ’\Memory\Available Bytes’, `
      ‘\PhysicalDisk(_Total)\% Disk Time’

3a

4. MS Excel is a powerful tool. Can PS export data into a format Excel can use? Yes it can! This example uses the Quest ActiveRoles Management Shell for Active Directory (ARMS), but you could also use get-user from the Exchange PS management tools, etc., then export the results to a comma separated value (CSV) file that Excel can import:

Get-QADUser | Export-Csv -NoTypeInformation -Encoding OEM users.csv

4a

MS Excel can open the resulting file, and you can sort, filter, etc., as you normally would inside Excel.

5. All of the examples I have given show how to read data, but what if you want to write data back into AD? No problem! Just combine the earlier examples to gather your data, then send the results into the built-in MS tool dsmod.exe:

5a

And, since I am encouraging you to mix-and-match tools, what if you want to use the Quest ARMS commands and the Exchange cmdlets (for example) at the same time? Here’s a command that will load all of the PS modules you have installed on your system into a single PS session. Open up a PS window and use this command, courtesy of the Microsoft Scripting Guys:

Get-Module -ListAvailable | Import-Module

6a

Just a caveat for those of you running Exchange 2007 or 2010: These products have not been updated to use v3 of PowerShell yet, so hold off installing it until MS says it is safe.

And for those of you who looked at remoting in v2: PS v2 introduced remoting, but v3 makes the whole thing more robust and reliable. If v2 remoting left you with a bad taste, give it a fresh try with v3 – I guarantee you will have a better experience!

John Scaggs, MCT, MCITP

Senior Consultant, Advanced Infrastructure Group

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