ErrorVariable, Parameter

It is said that we learn from our mistakes, and that to improve learning it’s best to write things down. How about storing our mistakes and errors in a variable? If that’s not killing two flies with one stone, at least it’s a useful feature of PowerShell. Let’s use it and see how it works, using the Stop-Service cmdlet we try to stop a service:

PS C:\> Stop-Service -name XAudioService -ErrorVariable myErrors
Stop-Service : Service 'XAudioService (XAudioService)' cannot be stopped due to the following error: Cannot open XAudio
Service service on computer '.'.
At line:1 char:13
+ Stop-Service <<<

As you can see the error is also written to screen. From now on we can reference the error in the $myErrors variable we created:

PS C:\> $myErrors
Stop-Service : Service 'XAudioService (XAudioService)' cannot be stopped due to the following error: Cannot open XAudio
Service service on computer '.'.
At line:1 char:13
+ Stop-Service <<<

You might want to know that even if you don’t specify the -ErrorVariable parameter all the errors will be storied in a special error called $error.

Saving the error variable like we have done above will ensure that you have the last error saved. One thing you can do is to add a plus sign before the variable when you want to append to the error variable. Here is an example:

PS C:\> Stop-Service -name XAudioService -ErrorVariable +myError
PS C:\> Stop-Service -name WinRM -ErrorVariable +myError
PS C:\> $myError.Count
2
PS C:\>