Powershell, pass an answer to a script that requires a choice-CodePudding

I have a PowerShell script that has a y/n question asked in the script. I cannot change the script as it is downloaded from a url, but I would like to run it such that my choice is passed to the script and processing continues unattended.

I found this question, which is on a similar topic, but more related to cmdlets (and I tried everything here, but no luck).

Here is the relevant code (say this is in a script test.ps1)

function Confirm-Choice {
    param ( [string]$Message )
    $yes = New-Object System.Management.Automation.Host.ChoiceDescription "&Yes", "Yes";
    $no = New-Object System.Management.Automation.Host.ChoiceDescription "&No", "No";
    $choices = [System.Management.Automation.Host.ChoiceDescription[]]($yes, $no);
    $caption = ""   # Did not need this before, but now getting odd errors without it.
    $answer = $host.ui.PromptForChoice($caption, $message, $choices, 1)   # Set to 0 to default to "yes" and 1 to default to "no"
    switch ($answer) {
        0 {return 'yes'; break}  # 0 is position 0, i.e. "yes"
        1 {return 'no'; break}   # 1 is position 1, i.e. "no"
    }
}

$unattended = $false   # default condition is to ask user for input
if ($(Confirm-Choice "Prompt all main action steps during setup?`nSelect 'n' to make all actions unattended.") -eq "no") { $unattended = $true }

i.e. Without altering the script, I would like to pass 'n' to this so that it will continue processing. Something like test.ps1 | echo 'n' (though, as before, this specific syntax does not work unfortunately, and I'm looking for a way to do this).

CodePudding user response：

PromptForChoice appears to read input directly from the console host, so it can't be supplied with input from stdin.

You may override the function Confirm-Choice instead, by defining an alias that points to your own function which always outputs 'n'. This works because aliases take precedence over functions.

function MyConfirm-Choice {'no'}
New-Alias -Name 'Confirm-Choice' -Value 'MyConfirm-Choice' -Scope Global

.\test.ps1   # Now uses MyConfirm-Choice instead of its own Confirm-Choice

# Remove the alias again
Remove-Item 'alias:\Confirm-Choice'