Powershell：同名参数为命令定义了多次

Question

Any idea, how to get a Switch running with Powershell?

myscript.ps1 -Debug

A parameter with the name 'Debug' was defined multiple times for the command.

My Script

    [CmdletBinding()]
    Param (
        [switch]$Debug
    )
    
    if ($Debug) {
     Start-Transcript -Path "Debug.log" -Append -Force
}

Answer 1

When you create an advanced function or script that uses the CmdletBinding attribute or the Parameter attribute, PowerShell adds common parameters , including -Debug to your function. So you should not add these on your own.

To test for the -Debug common parameter, it is more flexible to check the value of the related preference variable $DebugPreference . This works because -Debug overrides $DebugPreference within the scope of the script.

[CmdletBinding()]
Param ()
    
if( $DebugPreference -eq 'Continue' ) {
    Start-Transcript -Path "Debug.log" -Append -Force
}

Now you can enable debug logging for your script either using the parameter...

.\myscript.ps1 -Debug

... or the preference variable:

$DebugPreference = 'Continue'
.\myscript.ps1