PowerShell: Start-Process cmdlet, but with support of -CaptureOutput and -RedirectToStdout flags.

Start-ProcessExt.psm1

#Requires -Version 7.4
#Requires -PSEdition Core

$ErrorActionPreference = 'Stop'
Set-StrictMode -Version Latest

<#
.SYNOPSIS
The same as Start-Process but with support of -CaptureOutput and -RedirectToStdout parameters.

.OUTPUTS
Output of the process if -CaptureOutput was specified or process object if -PassThru and -Wait was specified.
#>
function Start-ProcessExt {
    [CmdletBinding()]
    [OutputType([string[]])]
    param (
        # File path of the executable.
        [Parameter(Mandatory = $true)]
        [string]
        $FilePath,

        # Argument list.
        [Parameter()]
        [string[]]
        $ArgumentList,

        # Location where the new process should start in.
        [Parameter()]
        [string]
        $WorkingDirectory,

        # Capture output?
        [Parameter()]
        [switch]
        $CaptureOutput,

        # Redirect all output to stdout?
        [Parameter()]
        [switch]
        $RedirectToStdout,

        # Wait for the program to finish execution?
        [Parameter()]
        [switch]
        $Wait,

        # Execute process in the same console window?
        [Parameter()]
        [switch]
        $NoNewWindow,

        # Return process object?
        [Parameter()]
        [switch]
        $PassThru,

        # Verb to use.
        [Parameter()]
        [string]
        $Verb
    )

    # Expand FilePath to full form.
    $FilePath = Resolve-Path -Path $FilePath

    # Verify parameters.
    if ($CaptureOutput -and -not $Wait) {
        throw 'Unable to use -CaptureOutput without -Wait parameter'
    }
    if ($CaptureOutput -and -not $NoNewWindow) {
        throw 'Unable to use -CaptureOutput without -NoNewWindow parameter'
    }
    if ($CaptureOutput -and $PassThru) {
        throw 'Unable to use -CaptureOutput with -PassThru parameter, refer to $LastExitCode instead'
    }
    if ($CaptureOutput -and $Verb) {
        throw 'Unable to use -CaptureOutput with -Verb parameter'
    }
    if ($RedirectToStdout -and -not $CaptureOutput) {
        throw 'Unable to use -RedirectToStdout without -CaptureOutput parameter'
    }
    if ($Verb -and $NoNewWindow) {
        throw 'Unable to use -Verb with -NoNewWindow parameter'
    }

    if ($CaptureOutput) {
        # Change directory.
        if ($WorkingDirectory) {
            Push-Location -Path $WorkingDirectory
        }

        # Start process, capture output, wait to finish.
        if ($RedirectToStdout) {
            & $FilePath $ArgumentList *>&1
        } else {
            & $FilePath $ArgumentList
        }

        # Change directory to previous.
        if ($WorkingDirectory) {
            Pop-Location
        }
    } else {
        # Build Start-Process commandlet conditional arguments.
        $startProcessCondArgs = @{}
        if ($Wait) {
            $startProcessCondArgs.Add('Wait', $true)
        }
        if ($NoNewWindow) {
            $startProcessCondArgs.Add('NoNewWindow', $true)
        }
        if ($WorkingDirectory) {
            $startProcessCondArgs.Add('WorkingDirectory', $WorkingDirectory)
        }
        if ($PassThru) {
            $startProcessCondArgs.Add('PassThru', $true)
        }
        if ($Verb) {
            $startProcessCondArgs.Add('Verb', $Verb)
        }

        # Start process, skip output.
        Start-Process -FilePath $FilePath -ArgumentList $ArgumentList @startProcessCondArgs
    }
}