Powershell trap [Exception] is not catching my error

Question

For some reason my script is not catching the exception when I run the following script against a file that does not exist. I based this code from examples I found on the web but it doesn't seem to work for me.

I would appreciate any tips or pointers on how to fix this.

Note: in the example below I've also tried

trap [Exception] {

but that didn't work either.

Here's the script:

function CheckFile($f) {

      trap {
        write-host "file not found, skipping".
        continue
      }

      $modtime = (Get-ItemProperty $f).LastWriteTime

      write-host "if file not found then shouldn't see this"
}


write-host "checking a file that does not exist"
CheckFile("C:\NotAFile")
write-host "done."

output:

PS > .\testexception.ps1
checking a file that does not exist
Get-ItemProperty : Cannot find path 'C:\NotAFile' because it does not exist.
At C:\Users\dleclair\Documents\Visual Studio 2010\lib\testexception.ps1:12 char:35
+       $modtime = (Get-ItemProperty <<<<  $f).LastWriteTime
    + CategoryInfo          : ObjectNotFound: (C:\NotAFile:String) [Get-ItemProperty], ItemNotFoundException
    + FullyQualifiedErrorId : PathNotFound,Microsoft.PowerShell.Commands.GetItemPropertyCommand

if file not found then shouldn't see this
done.
PS >

Answer 1

Try like this:

trap { write-host "file not found, skipping";continue;}
$modtime = Get-ItemProperty c:\manoj -erroraction stop

Based on comments from OP:

I think you misunderstood what is being said in the article you have linked to:

In this example, we used continue to caused execution to return to the scope the trap is in and execute the next command. It’s important to note that execution only returns to the scope of the trap, so if the exception was thrown inside a function, or even inside a if statement, and trapped outside of it … the continue will pick up at the end of the nested scope.

So if you do something like this:

trap{ write-host $_; continue;}
throw "blah"
write-host after

after will be printed.

But if you do something like this:

trap{ write-host $_ ; continue}
function fun($f) {


      throw "blah"
      write-host after
}

fun
write-host "outside after"

after will NOT be printed, but outside after will be.

Alternatively, use a try-catch block:

      try{
      $modtime = (Get-ItemProperty $f -erroraction stop).LastWriteTime
      write-host "if file not found then shouldn't see this"
      }
      catch{
        write-host "file not found, skipping".
      }

Answer 2

You have to set $ErrorActionPreference to SilentlyContinue inside of the function or outside of the script (for global application) for trap to work. Alternatively (as mentioned above), set -ErrorAction common parameter to the same thing.