Windows 7 / Getting Started

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Script Reusability

I used the variable $Name in the script used in previous. After all, instead of these two lines:

$Name = "WinDefend"
Get-service | Select * | Where {$_.name -eq $Name }

Used just this line:

Get-service | Select * | Where {$_.name -eq "WinDefend }

The reason is for script reusability. Although this code was written for the Windows Defender service, it can easily be used for any service. The only thing that needs to change is the name of the service.

For example, if I wanted to use this for a different service, such as the Print Spooler service, I'd just need to identify the name of the Print Spooler service (Spooler) and put it in place of "WinDefend" in the $Name = "WinDefend" line as $Name = "Spooler".

It's even possible to use the Param command to allow the script to accept a parameter. In other words, I can name my script CheckService and program it to accept the name of a service as Param($svc). I could check the Windows Defender service with the command CheckService WinDefend or the Print Spooler service with the command CheckService Spooler.

To put it all together, I added a couple of extra touches to this script. This script checks to see if the service is running, and if so, it restarts it (which can sometimes be useful for services that hang, like the Print Spooler service). If the service is stopped, it will be started.

If it is paused, it'll be resumed.

Listing below shows it in full.

Check status of service

#Script written Sep 2009 by Mike Gibson
#Purpose. Checks status of service.
# Restarts if running, starts if stopped,
# and resumes if paused.
#Expects Display Name of service
# as a parameter ($Name)
Param($Name)
$svc = Get-service | Select * | Where {$_.name -eq $Name}
$status = $svc.status
# Write-Host $svc.Name "service is" $status
Switch ($Status) {
"Running" {Restart-Service $Name }
"Stopped" { Start-Service $Name }
"Paused" {
#Windows Defender can't be paused or resumed
Resume-Service $Name }
}

Notice the use of the Param command. Instead of hard-coding the name of the service, it accepts a parameter (such as WinDefend or Spooler). The Param command must be the very first executable line (comments can precede it). You would execute the script from PowerShell as

c:\scripts\CheckService.ps1 WinDefend

The script can also be called from other programs including Task Scheduler, as was shown with a batch file earlier in the tutorial.

However, you'll find that this script won't work completely unless you run it with elevated permissions. For example, if the Windows Defender service is running, the script will try to restart it but can't because it doesn't have permissions. Instead, launch the script from a PowerShell window with elevated permissions by selecting Run As Administrator or execute it with the System account when executed from a program such as Task Scheduler.

Well, that's a taste of Windows PowerShell. Don't expect to walk away with a full understanding of everything that can be done with PowerShell. However, if you come across any PowerShell commands or scripts, they should make a little more sense to you.