Check if in debug mode in PowerShell
Here's a function which allows you easily check; along with a few options to alter the behaviour.
function Test-Debug { [CmdletBinding()] param ( [Parameter(Mandatory = $false)] [switch]$IgnorePSBoundParameters , [Parameter(Mandatory = $false)] [switch]$IgnoreDebugPreference , [Parameter(Mandatory = $false)] [switch]$IgnorePSDebugContext ) process { ((-not $IgnoreDebugPreference.IsPresent) -and ($DebugPreference -ne "SilentlyContinue")) -or ((-not $IgnorePSBoundParameters.IsPresent) -and $PSBoundParameters.Debug.IsPresent) -or ((-not $IgnorePSDebugContext.IsPresent) -and ($PSDebugContext)) }}Here's some code to demonstrate output in certain scenarios:
#region 'Test Functions'function Test-InheritExplicit { [CmdletBinding()] param ( [Parameter(Mandatory = $false)] [switch]$IgnorePSBoundParameters , [Parameter(Mandatory = $false)] [switch]$IgnoreDebugPreference , [Parameter(Mandatory = $false)] [switch]$IgnorePSDebugContext ) process { #if we weren't splatting all vars over, we could use this trick: #[switch]$DebugCopy = $PSBoundParameters.Debug #Test-Debug -Debug:$DebugCopy Test-Debug @PSBoundParameters }}function Test-InheritImplicit { [CmdletBinding()] param ( [Parameter(Mandatory = $false)] [switch]$IgnorePSBoundParameters , [Parameter(Mandatory = $false)] [switch]$IgnoreDebugPreference , [Parameter(Mandatory = $false)] [switch]$IgnorePSDebugContext ) process { Test-Debug -IgnorePSBoundParameters:$IgnorePSBoundParameters -IgnorePSDebugContext:$IgnorePSDebugContext -IgnoreDebugPreference:$IgnoreDebugPreference }}#endregion 'Test Functions'#region 'Test Cases'[hashtable[]]$testCases = 0..15 | %{ [hashtable]$new = @{} if ($_ -band 1) {$new.Debug = [switch]$true} if ($_ -band 2) {$new.IgnorePSBoundParameters = [switch]$true} if ($_ -band 4) {$new.IgnoreDebugPreference = [switch]$true} if ($_ -band 8) {$new.IgnorePSDebugContext = [switch]$true} $new}[int]$t = 0$testCases | %{ [hashtable]$testCase = $_ (New-Object -TypeName PSObject -Property @{ TestId = ++$t Debug = [bool]$_.Debug IgnorePSBoundParameters = [bool]$_.IgnorePSBoundParameters IgnoreDebugPreference = [bool]$_.IgnoreDebugPreference IgnorePSDebugContext = [bool]$_.IgnorePSDebugContext TD = (Test-Debug @testCase) TIE = (Test-InheritExplicit @testCase) TII = (Test-InheritImplicit @testCase) })} | Format-Table TestId, Debug, IgnorePSBoundParameters, IgnoreDebugPreference, IgnorePSDebugContext, TD, TIE, TII -AutoSizeHere's the output from the above:
TestId Debug IgnorePSBoundParameters IgnoreDebugPreference IgnorePSDebugContext TD TIE TII------ ----- ----------------------- --------------------- -------------------- -- --- --- 1 False False False False False False False 2 True False False False True True True 3 False True False False False False False 4 True True False False True True True 5 False False True False False False False 6 True False True False True True False 7 False True True False False False False 8 True True True False False False False 9 False False False True False False False 10 True False False True True True True 11 False True False True False False False 12 True True False True True True True 13 False False True True False False False 14 True False True True True True False 15 False True True True False False False 16 True True True True False False False
"Debugged" in PowerShell could mean several things. 1) The program is running under a debugger, 2) The cmdlet/function is passed -Debug flag or $DebugPreferences is not SilentlyContinue 3) PowerShell tracing is on, 4) Set-PSDebug was used to toggle tracing (a different kind of tracing than #3).
If you haven't chosen one of these already, I suggest you pick #2. It is straightforward (check if -Debug is in PSBoundVariables or value of $DebugPreferences is not SilentlyContinue). It supports Write-Debug cmdlet. In general terms, it is the PowerShell-ish way to toggle debug output.
If you really need #1, then as this page explains, implementing a PowerShell debugger at its core is handling two events (Debugger.BreakpointUpdated and Debugger.DebuggerStop), so you need to see if there is a handler for these events.
If you need #4, you'll probably need to access private data. The only PowerShell 3.0 command with PSDebug as the noun is Set-PSDebug, which means there isn't a cmdlet to return the state of PSDebug.
If you need #3, then the situation is similar to #4. There aren't cmdlets to return information of what's being traced.
Example template script with backward compatibility (and a little commenting)
# turn regular script into advanced script by adding the cmdletbinding attribute and its required param()[CmdletBinding()]Param()$DebugPreferenceWas = $DebugPreference# $debugPreference is default to "SilentlyContinue"# if -debug argument passed, we get "$DebugPreference=Inquire"if ($DebugPreference -ne "SilentlyContinue" -And $PSVersionTable.PSVersion.Major -lt 6) { # note: for backward compatibility set $DebugPreference='Continue' # prior to PowerShell 6, we would have to answer a question for each Debug message, this change in v6 Write-Output "Backward compatibility, update DebugPreference" $DebugPreference = 'Continue' Write-Output "DebugPreference was: $DebugPreferenceWas, changed to: $DebugPreference"}Write-Debug "this line will only print if -Debug was passed to the script"Write-Output "script ran, exiting"So, like we do the check, you could do something like:
[CmdletBinding()]Param()# ... some code here creating variables or whatnot ...if ($DebugPreference -ne "SilentlyContinue") { # in debug $messageProperties.To = "$env:username@company.com"} else { # not debug $messageProperties.To = "prodmailbox@company.com"}