Permissions problem

[John R. Wicks]

I am running petsc-2.3.3-p3 on two platforms (Debian GNU/Linux 4.0 and Mac
OS Server 10.4.10) installed in a shared NFS directory.  While I can get
mpdboot to run on both platforms, and I can run multi-machine programs using
mpiexec under Linux, when I try to do it on the Mac, I get a permissions
error:

newton ~/pweb/C % mpiexec -n 5 t
problem with execution of t  on  poinsot.ilab.cs.brown.edu:  [Errno 13]
Permission denied
problem with execution of t  on  pell.ilab.cs.brown.edu:  [Errno 13]
Permission denied
problem with execution of t  on  newton.ilab.cs.brown.edu:  [Errno 13]
Permission denied
problem with execution of t  on  pell.ilab.cs.brown.edu:  [Errno 13]
Permission denied
problem with execution of t  on  newton.ilab.cs.brown.edu:  [Errno 13]
Permission denied

What permissions does this need?