You might want to try using cmd to capture the output? you can try
STRING cmd web.exe > pw.txt
that may be a simple fix, however if you are still not capturing the information, you may wish to try
STRING cmd web.exe > pw.txt 2>&1
this means that you will capture the error output as well (where it may be getting written). For a more detailed description have a look into Stream 1 (STDOUT) and stream 2 (SDTERR) outputs.
hope that helps