my ArkHost.run() woes -- fork/dup/pipe/etc bite back

The 'run' method for an ArkHost runs a bit of code on the
host.  Since the beginning, the code has been:

    sh = os.popen(start_shell,'w')
    sh.write(code)

where 'start_shell' is one of:

1  /bin/sh
2  sudo -u <user> /bin/sh
3  ersh <host> /bin/sh
4  ersh <host> sudo -u <user> /bin/sh

and then we shovel the desired shell script into it.

Downsides are two:

a. the stdout/stderr of the code that gets run just flies
   about aimlessly... wouldn't it be nice to grab it and
   "plumb" it in with the normal Python-interpreter
   stdout/stderr?

b. If we do that, then it's a short step to being able to
   replace sys.stdout and sys.stderr with objects that suck
   up the data, which we can then look at.  **This is very
   very nice for testing**!  (Urgh; this is a potential
   upside, not a downside...)

I've messed around with two sets of code, both of which you
will find in ARK/arkbase/ark/utils.py (next to host.py).

- runCmd() is some code of Jonathan's that does
  fork/exec/dup/close -- the full Unix thing.

- runCmd2(): something I did that isn't a long way from
  Jonathan's, except based around the Popen3 object that
  Python provides...

For reasons I cannot fathom, both of these have serious
problems with some of cases 2-4; i.e. they work for "the
obvious", but fail for the sudo/ersh cases.

I would *really* like to overcome the "downsides"... anyone
got any ideas?

Will