Capturing verbose output from -Verbose switch in PowerShell v2

Question

I ran into an interesting issue today that has me puzzled. I need to capture output from the verbose stream and write it to stdout.

This can be accomplished with this:

# Create a PowerShell Command 

$pscmd = [PowerShell]::Create() 

# Add a Script to change the verbose preference. 
# Since I want to make sure this change stays around after I run the command I set UseLocalScope to $false. 
# Also note that since AddScript returns the PowerShell command, I can simply call Invoke on what came back. 
# I set the return value to $null to suppress any output 

$null = $psCmd.AddScript({$VerbosePreference = "Continue"},$false).Invoke() 

# If I added more commands, I'd be adding them to the pipeline, so I want to clear the pipeline 

$psCmd.Commands.Clear() 

# Now that I've cleared the pipeline, I'll add another script that writes out 100 messages to the Verbose stream 

$null = $psCmd.AddScript({Write-verbose "hello World" }).Invoke() 

# Finally, I'll output the stream 

$psCmd.Streams.Verbose

Now the interesting part is if I were to create a function called Hello-World and use [CmdletBinding()] to inherit the -verbose switch, I can no longer capture output:

Function Hello-World {
    [CmdletBinding()]
    Param()

    Write-Verbose "hello world"
}

...
$null = $psCmd.AddScript({Hello-World -Verbose }).Invoke() 
...

I am assuming that the function is given its own verbose stream and that visibility to the stream is lost, but I am not positive. Does this have to do with [CmdletBinding()]?

Avoiding transcripts, is there a way to accomplish this?

Thanks!

Are you sure the function is executing properly? It may be that the function isn't defined in the new powershell instance you're dealing with. — Jason Morgan
– Jason Morgan, Commented Jul 30, 2014 at 17:38
Also, within an advanced function ([CmdletBinding()]) you should be using $pscmdlet.WriteVerbose("Hello World") — Keith Hill
– Keith Hill, Commented Jul 30, 2014 at 17:42

Jason Bristol · Accepted Answer · 2014-07-30 17:48:42Z

2

Thank you @JasonMorgan, below is the solution that appears to be working. I needed to declare the function in the pscmd I made:

$pscmd = [PowerShell]::Create() 

$null = $psCmd.AddScript({$VerbosePreference = "Continue"},$false).Invoke()
$null = $psCmd.AddScript({
  function Hello-World {
    [CmdletBinding()]
    Param()
    Write-Verbose "hello world"
  }
}, $false).Invoke() 

$psCmd.Commands.Clear() 

$null = $psCmd.AddScript({Hello-World -Verbose }).Invoke() 

$psCmd.Streams.Verbose

answered Jul 30, 2014 at 17:48

Jason Bristol

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