Catching errors in powershell workflow

Question

I'm relatively new to powershell scripting so I have been coding based on multiple examples that I have seen online.

I have a script that executes multiple batch files in parallel and each batch file contains a bcp command to execute. I'm trying to catch any errors that may occur running the batch file but it's not working as expected. I specifically forced an error on product.bat by having an invalid select syntax.

workflow Test-Workflow 
{
    Param ([string[]] $file_names)
    $file_names = Get-Content "D:/EDW/data/informatica/ming/Powersh/bcplist.lst"
    foreach -parallel ($line in $file_names) 
    {
       try
       {
          Write-Output ("processing... " + $line + ".bat")
          start-process D:/EDW/data/informatica/ming/Powersh/$line.bat -ErrorAction Stop -wait
       }
       catch
       {
          $ErrorMessage = $_.Exception.Message
          $FailedItem = $_.Exception.ItemName
          Write-Output $line : $ErrorMessage  $FailedItem
       }
   }
}

bcplist.lst:
        ing_channel
        ing_product

ing_channel:
        bcp "SELECT  * FROM CHANNEL" queryout ing_channel.txt -T -S99.999.999.9,99999 -t"\t" -c -q

ing_product:
        bcp "SELT  * FROM PRODUCT" queryout ing_product.txt -T -S99.999.999.9,99999 -t"\t" -c -q

Any help or suggestion would be greatly appreciated.

BAT files are not PoSh code ... and they don't trigger a stop error ... and the try/catch construct REQUIRES a stop error. ///// why are you using BAT files? the bcp.exe util should run properly when called from in a ps1 file. ///// also, the bcp.exe util seems to be doing SQL queries ... and powershell has cmdlets for that ... so, why use that util instead of the PoSh cmdlets? — Lee_Dailey
– Lee_Dailey, Commented Dec 27, 2019 at 15:20

codewario · Accepted Answer · 2019-12-27 15:41:06Z

2

Exceptions are only thrown/caught when terminating errors are thrown, which are only thrown by cmdlets, .NET libraries, or native code when P/Invoke is in play. In order to handle failures with external commands, such as checking whether a bat or exe succeeded, you will need to check the $LASTEXITCODE yourself. $LASTEXITCODE is the PowerShell equivalent of %ERRORLEVEL% in cmd.exe. Here is an example of some basic boilerplate code to check this for the ping command:

&ping nonexistant.domain.tld
if( $LASTEXITCODE -ne 0 ){
  # Handle the error here
  # This example writes to the error stream and throws a terminating error
  Write-Error "Unable to ping server, ping returned $LASTEXITCODE" -EA Stop
}

Note that the -ErrorAction argument has a shorthand of -EA, so either the long or short form will work.

edited Dec 27, 2019 at 15:41

answered Dec 27, 2019 at 15:33

codewario

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