[Kazun]

Лучше использовать .Net:

Код:

$cmd = "a " + ($curent_dir + $filename + ".zip" ) + " " + ($source_dir + $dir + '\' + $filename)
$pi = New-Object Diagnostics.ProcessStartInfo -Property @{
	FileName = $arhivator
	Arguments = $cmd
}

$pr = [Diagnostics.Process]::Start($pi)
$pr.WaitForExit()
$pr.ExitCode