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


Here the writebytes.d script is run for a few seconds, then Ctrl-C is hit,

   # writebytes.d
   dtrace: description 'sysinfo:::writech ' matched 4 probes
   ^C
     dtrace                                                            1
     gnome-settings-d                                                  8
     xscreensaver                                                      8
     gnome-panel                                                       8
     nautilus                                                          8
     date                                                             29
     wnck-applet                                                     120
     bash                                                            210
     mozilla-bin                                                    1497
     ls                                                             1947
     metacity                                                       3172
     Xorg                                                           7424
     gnome-terminal                                                51955


In this interval the gnome-terminal command has successfully written 51.9 Kb, 
while Xorg has written 7424 bytes.