Try-catch issue powershell

Question

function Test($cmd)
{
          Try
         {
                  Invoke-Expression $cmd -ErrorAction Stop
         }
         Catch
         {
                  Write-Host "Inside catch"
         }

         Write-Host "Outside catch"
}

$cmd = "vgc-monitors.exe"  #Invalid EXE
Test $cmd

$cmd = "Get-Content `"C:\Users\Administrator\Desktop\PS\lib\11.txt`""
Test $cmd

#

Call Test() first time with $cmd = "vgc-monitors.exe" (this exe does not exist in system)

*Exception caught successfully

*Text "Inside catch" "outside catch" printed

#

Call Test() second time with $cmd = "Get-Content "C:\Users\Administrator\Desktop\PS\lib\11.txt"" (11.txt does not exist in the specified path)

*Exception NOT caught

*Text "Inside catch" not printed"

*Get the following error message

Get-Content : Cannot find path 'C:\Users\Administrator\Desktop\PS\lib\11.txt' because it does not exist.
At line:1 char:12
+ Get-Content <<<<  "C:\Users\Administrator\Desktop\PS\lib\11.txt"
    + CategoryInfo          : ObjectNotFound: (C:\Users\Admini...p\PS\lib\11.txt:String) [Get-Content], ItemNotFoundEx
   ception
    + FullyQualifiedErrorId : PathNotFound,Microsoft.PowerShell.Commands.GetContentCommand

Question:

I want the second exception to be caught. I cannot figure out the error in my code.

Thanks

Jugari

Ansgar Wiechers · Accepted Answer · 2013-09-03 14:12:50Z

2

You're applying -ErrorAction Stop to Invoke-Expression, which executes just fine. To make the error action directive apply to the invoked expression you'd need to append it to $cmd:

Invoke-Expression "$cmd -ErrorAction Stop"

or set $ErrorActionPreference = "Stop":

$eap = $ErrorActionPreference
$ErrorActionPreference = "Stop"
try {
  Invoke-Expression $cmd
} catch {
  Write-Host "Inside catch"
}
$ErrorActionPreference = $eap

The latter is the more robust approach, as it doesn't make assumptions about $cmd.

edited Sep 3, 2013 at 14:12

answered Sep 2, 2013 at 14:01

Ansgar Wiechers

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3 Comments

Keith Hill Over a year ago

What if $cmd happens to be an exe? Or for some reason they decided to end the command with a ;?

Ansgar Wiechers Over a year ago

@KeithHill Then he'd just have to stick with second option I suggested.

Keith Hill Over a year ago

That would be preferable I think. :-)

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