$pid = Run('"C:\ExcelCompare\ExcelComparer.exe"' & " " & $file1 & " " & $file2, "", @SW_HIDE, $STDERR_CHILD + $STDOUT_CHILD)
ProcessWaitClose("ExcelComparer.exe")
$out = StdoutRead($pid)
MsgBox(0, "STDOUT read:", $out)
Processwaitclose seems to work too. i'll give the loops a try later on. but the way the exe is coded, it gives an stdout stream at the very end of execution and not at intervals. so I don't think that i need to keep checking on regular intervals. anyway, i'll experiment some more. thanks a lot for you help, as usual.