Python Gtk2 & Vte wait for the process Pid is finish

I'm using the VTE module in a GTK window, to run and show the result of a bash script.

      adresse = self.champ.get_text()    
      pid = self.v.fork_command(None, ['/bin/bash', "./pluzz.sh", adresse])

      if pid == None:         #pseudocode
          print "Finish"

The child process is blocking (don't run) if there's time.sleep, or a loop. How can I do ? Thanks

Edit: Tried this:

def check_pid(pid):        
    """ Check For the existence of a unix pid. """
    try:
        os.kill(pid, 0)
    except OSError:
        return False
    else:
        return True

The problem is the return is once True, and if I write a loop, the bash script is blocking.

I've found a solution:

def __init__(self):
   a=0
   self.fenetre = gtk.Window(gtk.WINDOW_TOPLEVEL)
   [...]
   self.v = vte.Terminal()
#  self.v.connect ("child-exited", lambda term: gtk.main_quit())  # this is the line to change
   self.v.connect ("child-exited", lambda term: self.copie(self, a)) # the redirection after the process is finish
   self.v.show()

def download(self, a, donnees=None): 
   child_pid = self.v.fork_command(None, ['/bin/bash', "./pluzz.sh", adresse])

def copie(self, a, donnees=None):        
              print "FINISH"