Get ExitCode from Process in PowerShell While Redirecting StandardError

Question

I'm currently working on a PowerShell script that includes the line

$process1 = Start-Process -FilePath ($exePath1) -PassThru -RedirectStandardError ($logPath1)

Which starts a long-running process and redirects the process' StandardError to a log file. My problem is that this also apparently interferes with ExitCode.

$process1.ExitCode

returns null after the process has exited. If I remove "RedirectStandardError ($logPath1)" then ExitCode returns the value my dummy-program is expected to return.

Should I be doing something different? I'm hoping to be able to start the process (redirecting the StandardError to the log file for diagnostics), wait a few seconds to make sure it doesn't crash, and retrieve the ErrorCode in the event that it does.

use $process1.WaitForExit() firstly before obtaining the $process1.ExitCode. — t0mm13b
– t0mm13b, Commented Jan 17, 2018 at 20:45
@t0mm13b: I'm using $process1.HasExited. The process in question is very vulnerable to configuration mistakes, so I want to start it up and make sure that it didn't crash out. — dornadigital
– dornadigital, Commented Jan 17, 2018 at 20:48

Maximilian Burszley · Accepted Answer · 2018-01-17 21:19:05Z

1

If you need to wait for the process and you're not running it as a different user:

$StartParams = @{
    FilePath = $exePath1
    RedirectStandardError = $logPath1
    PassThru = $True
    Wait = $True
}
$ReturnCode = (Start-Process @StartParams).ExitCode

Since it's long-running, here's an alternative method with PSJobs:

$Job = Start-Job -ScriptBlock {
    $StartParams = @{
        FilePath = $exePath1
        RedirectStandardError = $logPath1
        PassThru = $True
        Wait = $True
    }
    (Start-Process @StartParams).ExitCode
}
If ($Job.State -eq 'Completed')
{
    $ReturnCode = Receive-Job -Job $Job
}

edited Jan 17, 2018 at 21:19

answered Jan 17, 2018 at 21:01

Maximilian Burszley

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5 Comments

dornadigital Over a year ago

Upvote for the "Wait" idea, but this unfortunately doesn't work for me since the process in question is long-lived; I can't have my script hang waiting for it to possibly error out.

EBGreen Over a year ago

Kick off a child script as a job to do this bit then?

dornadigital Over a year ago

This partially works although the behavior is... odd. First off, you can't access variables from an outer scope, so I had to pass them in. Now it launches my console app, but no output is written to the console even on a Flush. I know that it's working, but nothing is shown. The weirdest thing though, is that $Job.State -eq 'Completed' actually returns true, even though -Wait is included. $Job.Error returns null. Any thoughts?

Maximilian Burszley Over a year ago

Oh that's right. Make sure you include the $using scope or you have to pass them in as arguments. @dornadigital As to your other concerns, does your console app write to stdout? Might want to try launching a new window. I assumed your exe was non-interactive considering how you're trying to run things.

dornadigital Over a year ago

Using $Job = Start-Job -ArgumentList $exePath1, $logPath1 -ScriptBlock { invoke-expression ("cmd /c start powershell -Command {(Start-Process -FilePath '" + $args[0] + "' -RedirectStandardError '" + $args[1] + "' -PassThru -Wait).ExitCode}") } launches everything as I'd expect, but I can't seem to access the ExitCode again. Receive-Job -Job $Job just returns null. Is this one of those speed and position problems, where you can know one but not the other?

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