Understanding Write-Verbose and Write-Debug

Question

Hi,

[CmdletBinding()] 
Param( 
) 
$CurrentVerbosePreference = $VerbosePreference 
$CurrentDebugPreference = $DebugPreference 
Write-Host "$VerbosePreference" 
Write-Host "$DebugPreference" 
$VerbosePreference = "Continue" 
$DebugPreference = "Continue" 
Write-Host "$VerbosePreference" 
Write-Host "$DebugPreference" 
Write-Verbose "Verbose" 
Write-Debug "Debug" 
$VerbosePreference = $CurrentVerbosePreference 
$DebugPreference = $CurrentDebugPreference 

Output:

PS C:\Windows\system32> & '\test.ps1' 
SilentlyContinue 
SilentlyContinue 
Continue 
Continue 
VERBOSE: Verbose 
DEBUG: Debug 
PS C:\Windows\system32> 

Why "VERBOSE" and "DEBUG" without command line options?

PS C:\Windows\system32> & '\test.ps1' -verbose 
Continue 
SilentlyContinue 
Continue 
Continue 
VERBOSE: Verbose 
DEBUG: Debug 
PS C:\Windows\system32>

Why "DEBUG"?

PS C:\Windows\system32> & '\test.ps1' -debug 
SilentlyContinue 
Inquire 
Continue 
Continue 
VERBOSE: Verbose 
DEBUG: Debug 

Why "VERBOSE"?

Thank you!

Answer 1

You'd have to add the necessary parameters to your script to manage the use of Write-Verbose and Write-Debug:

param(
    [switch]$Verbose,
    [switch]$Debug
)
# save the current preferences to restore later
$CurrentVerbosePreference = $VerbosePreference
$CurrentDebugPreference = $DebugPreference

# change verbose and/or debug preferences based on parameters
if ($Verbose){
    $VerbosePreference = 'Continue'
}
if ($Debug){
    $DebugPreference = 'Continue'
}

# you'll only see these if the corresponding parameter is used
Write-Verbose "I'm chatty!"
Write-Debug "Don't use me lightly!"

# cmdlet switches aren't affected and should produce the same output as the next two cmdlets
Get-ChildItem c:\junk\Untitled-22.ps1 -Verbose
Get-ChildItem C:\junk\Untitled-22.ps1 -Debug

# the same cmdlets, without the verbose/debug switches
Get-ChildItem c:\junk\Untitled-22.ps1
Get-ChildItem c:\junk\Untitled-22.ps1

$VerbosePreference = $CurrentVerbosePreference
$DebugPreference = $CurrentDebugPreference

Answer 2

The default values for $VerbosePreference and $DebugPreference are "SilentlyContinue". Your script changes the values to "Continue" for both. When you use the Write-Verbose and Write-Debug cmdlets the messages are displayed because you've made the choice for that to happen.

See here for more information: about_preference_variables

Answer 3

Thank you. Let me rephrase:

I expected that Write-Verbose will only write something if I run the script with '-verbose' and Write-Debug only if I run it with '-debug'. I want -debug only to write text and not inquire.
I want to have the option to get verbose output or even more verbose / debug output. What do I need to achieve that?

Thank you!

Answer 4

Ah, thanks a lot! I slightly adapted it and it now works as expected.

[CmdletBinding()]
Param(
    [Parameter()]
)

# Save Verbose / Debug preferences
$CurrentVerbosePreference = $VerbosePreference
$CurrentDebugPreference = $DebugPreference

if ($psBoundParameters['verbose']) {
    $VerbosePreference = 'Continue'
}
if ($psBoundParameters['debug']) {
    $DebugPreference = 'Continue'
    $VerbosePreference = 'Continue'
}