PowerShell Confirms

gistfile1.md

PowershellConfirmPreference / impact

• https://learn.microsoft.com/en-us/dotnet/api/system.management.automation.confirmimpact?view=powershellsdk-7.4.0

  • Operations with ConfirmImpact equal to or greater than $ConfirmPreference are confirmed
  • IF ConfirmImpact >= ConfirmPreference THEN prompt
  • Also:
    • Operations with ConfirmImpact.None are never confirmed
    • no operations are confirmed when $ConfirmPreference is ConfirmImpact.None (except when explicitly requested with -Confirm).

• https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_preference_variables?view=powershell-7.4

  • When the value of the $ConfirmPreference variable is less than or equal to the risk assigned to a cmdlet or function, PowerShell automatically prompts you for confirmation before running the cmdlet or function.
  • IF ConfirmPreference <= ConfirmImpact THEN prompt
  • IF ConfirmImpact > ConfirmPreference THEN prompt

• https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_functions_cmdletbindingattribute?view=powershell-7.4

  • The call to the ShouldProcess method displays a confirmation prompt only when the ConfirmImpact argument is equal to or greater than the value of the $ConfirmPreference preference variable.
  • IF ConfirmImpact >= ConfirmPreference THEN prompt

• https://learn.microsoft.com/en-us/powershell/scripting/developer/cmdlet/users-requesting-confirmation?view=powershell-7.4

  • If Confirm parameter is not used, the ShouldProcess() call requests confirmation if the $ConfirmPreference preference variable is equal to or greater than the ConfirmImpact setting of the cmdlet or provider.
  • IF ConfirmPreference >= ConfirmImpact THEN prompt
  • IF ConfirmImpact < ConfirmPreference THEN prompt

• https://github.com/PowerShell/PowerShell/blob/master/src/System.Management.Automation/engine/MshCommandRuntime.cs#L1456-L1461

  • IF ((threshold == ConfirmImpact.None) || (threshold > cmdletConfirmImpact)) THEN autoconfirm
  • => IF ConfirmPreference <= ConfirmImpact THEN prompt
  • IF ConfirmImpact > ConfirmPreference THEN prompt

Test-ShouldProcess.ps1

function Test-ShouldProcess {
    [CmdletBinding(
        SupportsShouldProcess,
        ConfirmImpact = 'High'
    )]
    param(
        [Switch]$Force
    )

    Write-Verbose  "`$PSCmdLet: $PSCmdLet"

    Write-Verbose "`$DebugPreference: $DebugPreference"
    Write-Verbose "`$ConfirmPreference: $ConfirmPreference"
    Write-Verbose "`$Confirm: $Confirm"
    Write-Verbose "`$Confirm: $($null -eq $Confirm ? "NULL": "NONNULL")"

    if ($Force -and -not $Confirm){
        Write-Verbose "Changing `$ConfirmPreference"
        $ConfirmPreference = 'None'
    } else {
        Write-Verbose "XXXX"
    }

    Write-Verbose "`$DebugPreference: $DebugPreference"
    Write-Verbose "`$ConfirmPreference: $ConfirmPreference"
    Write-Verbose "`$Confirm: $Confirm"
    Write-Verbose "`$Confirm: $($null -eq $Confirm ? "NULL": "NONNULL")"

    # Does this ignore $ConfirmPreference?
    # The call to $PSCmdlet.ShouldProcess($file.name) checks for the -WhatIf (and -Confirm parameter) then handles it accordingly.
    if ($PSCmdlet.ShouldProcess('TARGET')){
        Write-Output "Some Action"
    }

    if ($Force -or $PSCmdlet.ShouldContinue('TARGET','OPERATION')) {
        Write-Output "Some Action"
    }
}

<#
> $ConfirmPreference="Low" ; Test-ShouldProcess -force -confirm

Asks confirmation for ShouldProcess

> $ConfirmPreference="High" ; Test-ShouldProcess

Asks confirmation for both

> $ConfirmPreference="High" ; Test-ShouldProcess -Force

No confirmation asked

> $ConfirmPreference="High" ; Test-ShouldProcess -Force -Confirm

Asks confirmation for ShouldProcess

If both -Confirm and -Force are used Confirmation for ShouldProcess are requested.


Still logic of `if ($Force -and -not $Confirm){` does not make any sense and will not work on strict mode

#>