The following is a demonstration of the rwbbypid.d script,


Here we run it for a few seconds then hit Ctrl-C,

   # rwbbypid.d
   Tracing... Hit Ctrl-C to end.
   ^C
      PID CMD                       DIR            BYTES
    20347 bash                        R               22
    11053 dtrace                      W               32
     1532 Xorg                        W               64
    20317 sshd                        R               86
    20347 bash                        W               87
    20317 sshd                        W              137
     1659 mozilla-bin                 R              213
    20334 sshd                        R             1232
    20334 sshd                        W             1282
    11054 cp                          W            18652
    11054 cp                          R            18652
     1532 Xorg                        R            51112
     1659 mozilla-bin                 W            51261

In the above output, we can see that mozilla-bin with PID 1659 has written
51261 bytes, while Xorg has read 51112 bytes.