Here we go! It’s the third time doing what we can, to try and prove the usefulness and power in Windows PowerShell. With a little work, those new in PowerShell, get a glimpse into not only what they can do with PowerShell, but also why they’d want to do it with PowerShell. In the end, most of this is about time savings, and tonight’s post is no exception.
Part I can be found here. In that post, we learned that we could use PowerShell to create 10,000 folders in about 10 seconds — that’s 1,000 folders per second, or 1 folder each millisecond.
Part II is here. This post was about reading in a file’s contents, sorting the contents alphabetically, and then writing the sorted results back to the same file. PowerShell took milliseconds, while my manual attempt took minutes.
Part III
As part of my imaginary Windows PowerShell presentation I thought I might give one day, I always pictured a common theme — saving time. That’s a big part of why many of us have taken so fondly to PowerShell. I pictured telling a story about a few different approaches to the same problem, all to be completed by a different admin, each with their own best way of handling the request. Here’s my hypothetical, yet quite possible situation, beginning with the characters.
Admin One: This admin is fairly new to the industry. While they know their way around a desktop version of Windows, they’re still often learning new things about it. While they’re motivated, they haven’t learned enough to often know better.
Admin Two: This admin has a year or two on admin one, and is quickly picking up better ways to speed things up by utilizing certain tools.
Admin Three: This admin is getting there. It’s almost daily that they’re figuring out faster, and more remote ways to complete tasks. While they aren’t scripting and running commands (yet), they do know some tricks to get their results quicker.
Admin Four: This admin has been studying all things PowerShell whenever there’s a moment for it. Every task assigned is another challenge to learn more PowerShell, and to continue to add to their skills. They’re freeing up time, all the time.
One day the boss comes in with a request of the team. It’s not a difficult task. In fact, any one of the team members can get the task done. They need to check 200 of their computers to determine, and then document, which of the computers are running the print spooler service. Maybe it’s just busy work handed down by the boss, or maybe this is a valid concern somehow.
Admin One gets his clipboard and heads down to one of the computer labs. Once the three labs are checked, he’ll head to each of the offices to check those computers manually, too. Here’s the steps this admin takes: (1) Log on to the computer, (2) Open Computer Management, (3) Click on Services, (4) Find the Print Spooler service, noting the status, and (5) Write down the computer name and service’s status.
Let’s assume Admin One takes 5 minutes per computer which includes the time spent walking from computer to computer and office to office. At 200 computers, that’s 1,000 minutes, or approximately 16.6 hours. That’s longer than two full 8 hour days at the office. That kind of time loss equates to zero time spent learning anything new for two days in the week. You can’t stay in the field using this procedure.
Admin Two’s first though is Remote Desktop. While this admin still has to log on, it can be done without physically visiting each computer. In addition, this admin can work with more than one remote computer at a time. This allows Admin Two the ability to complete one computer every 2 1/2 minutes, cutting the time it takes Admin One in half. That’s only a little over one work day — 8.3 hours — lost to this project. While it’s shorter, it’s still too much time.
Admin Three knows enough to know that they can connect to a remote computer from inside Computer Management, which means they can also avoid leaving their desk. This removes the step of interactively logging on to a computer, and loading a desktop environment, too. We’ll assume this admin can do one computer every minute. That’s 200 total minutes, or 3.3 hours. That admin can actually finish before lunch if they start soon enough in the day. This might be reasonable by some boss’ standards, but PowerShell has been designed to do this quicker.
The final admin, Admin Four, knows PowerShell, and they know it well enough to pull back all those results without the need for any GUIs. There’s no wandering around the building, writing things down to a clipboard, or even entering data into a file, as Admin Two and Three do from their desks, as they use RDP and Computer Management, respectively.
Admin Four has a couple approaches and plenty of time to try them both out. While there’s many ways to read in computer names, we’ll assume they have a list of the 200 computers in a text file with each computer name on its own line. They may have had to build this file, but if they’re pulling from Active Directory, then it was probably automated, as well.
The first option is to use the Get-Service cmdlet, as seen below, in the first part of the example. The second part, which requires PowerShell Remoting, uses Invoke-Command. I’ve only include 20 computers in the computers.txt file, and to save space, only included 5 results per command in the example.
PS> # Uses the Get-Service cmdlet with -ComputerName parameter.
PS> # Have to add the MachineName property to see which results goes with which computer.
PS> Get-Service -ComputerName (Get-Content -Path .\computers.txt) -Name spooler | Select-Object MachineName,Status,Name,DisplayName
MachineName Status Name DisplayName
----------- ------ ---- -----------
DC01 Running spooler Print Spooler
DC02 Running spooler Print Spooler
DC03 Running spooler Print Spooler
WEB01 Running spooler Print Spooler
WEB02 Running spooler Print Spooler
...
PS> # Uses Invoke-Command which automatically adds the name of the remote computer by default.
PS> Invoke-Command -ComputerName (Get-Content -Path .\computers.txt) -ScriptBlock {Get-Service -Name spooler}
Status Name DisplayName PSComputerName
------ ---- ----------- --------------
Running spooler Print Spooler SQL01
Running spooler Print Spooler DC02
Running spooler Print Spooler DC02
Running spooler Print Spooler WEB02
Running spooler Print Spooler DC03
...
While I didn’t include the results, each of these two options — Get-Service, and Get-Service inside Invoke-Command — took about the same amount of time when they were measured. Even so, we’ll round up and say it takes 10 second for each set of 20 computers. At 200 computers, that 100 seconds for all of them. At 100 seconds, we’re talking about an approximation of 1 1/2 minutes to check all two hundred computers.
If I was in front of a crowd right now, and had just talked thought this post, I’d take a moment to ask the crowd which admin they thought would be around after budgets cuts. The admin that showed up with the results written down, after two days, or the one who sent the boss the results via email after two minutes? Keep in mind, that either of these cmdlets above can be used in conjunction with Export-Csv — a cmdlet that produces a text-based file that can be opened and edited with Microsoft Excel — something in which the boss probably has on their computer. In addition to automatically writing the results to file, by using the Send-MailMessage cmdlet, Admin Four can also automate sending the results by email.
