I am using the solution below. It handles stdout/stderr via transcript feature and passes exit code correctly to parent process. You need to adjust transcript path/filename.
If (-NOT ([Security.Principal.WindowsPrincipal][Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole] "Administrator"))
{
echo "* Respawning PowerShell child process with elevated privileges"
$pinfo = New-Object System.Diagnostics.ProcessStartInfo
$pinfo.FileName = "powershell"
$pinfo.Arguments = "& '" + $myinvocation.mycommand.definition + "'"
$pinfo.Verb = "RunAs"
$pinfo.RedirectStandardError = $false
$pinfo.RedirectStandardOutput = $false
$pinfo.UseShellExecute = $true
$p = New-Object System.Diagnostics.Process
$p.StartInfo = $pinfo
$p.Start() | Out-Null
$p.WaitForExit()
echo "* Child process finished"
type "C:/jenkins/transcript.txt"
Remove-Item "C:/jenkins/transcript.txt"
Exit $p.ExitCode
} Else {
echo "Child process starting with admin privileges"
Start-Transcript -Path "C:/jenkins/transcript.txt"
}
# Rest of your script goes here, it will be executed with elevated privileges