Creating a PowerShell Script

With the basics out of the way, it's time to walk through the creation of some basic scripts using the Windows PowerShell Integrated Scripting environment. Modified the Execution Policy so that scripts can be run.

Creating and Running a PowerShell Script

1. Launch the Windows PowerShell ISE.
2. Click in the top pane (labeled Untitled1.ps1), type in the following text, and press Enter:
   Get-EventLog -List
   Notice the command doesn't execute when you press Enter but instead starts a line 2.
3. Click the green button to run the script. You can also press F5. You'll see the result displayed in the middle pane. If there is a syntax error, you'll see a red text error instead of black text as the output.
   If you do see a red error message, look for these characters: <<<<. They will often point to the specific string of text that is causing the problem.
4. Click the Save icon on the menu (or press Ctrl+S). Browse to a folder named C:\ Scripts (create it if you need to), and change Untitled to LogInfo to save the script as C:\Scripts\LogInfo.ps1.
5. Move your cursor to the bottom of the screen, type C:\Scripts\LogInfo.ps1, and press Enter. The script will execute.
6. Change the current location to the script file with this command:
   Set-Location C:\Scripts.
7. Try to run the script with this command (it will fail):
   LogInfo.ps1
   Even though the script is in the current path, PowerShell needs a hint to find it.
8. Press the up arrow, and modify the last command so it looks like this:
   .\LogInfo.ps1
   The .\ characters tell PowerShell the script is in the current path.

Modifying a Script Using a ForEach Loop

1. Click File → New to create a blank area to work with a new script.
2. Enter the following text, and press F5 to execute it.
   get-service | select-object name, status
   This lists all the services on the system by name and their current status (such as running or stopped).
3. Instead of outputting this data to the screen, you can store it in a collection. The following command will store the result in a collection named $colService. Notice that you don't have to retype the entire command, but instead you just add $colService = to the beginning of the line:

   $colService = Get-service | select-object
     name, status

4. Now add a ForEach loop to loop through the collection. The loop will check each service stored in the collection and then use the Write-Host cmdlet to display only the services with a status equal to "running".

   ForEach ($item in $colService) {
       If ($item.status -eq "running")
       {write-host $item.name}
   }
   

Similarly, you could use the same method to list all the services that are stopped by simply changing "running" to "stopped" in the script.

While this example does show how a ForEach loop can be used to loop through a collection, it's not the only way to get a list of running services. As with most scripts, there's more than one way to get what you need. For example, the following one-liner could also be used to get a list of running services: