Hello all, I am trying to use two raspberry-pi to sample and then process some data. The first process samples while the second processes and vice versa. To do this I use gpio and also mpich-3.0.4 with the process manager smpd. I have successfully run cpi on both machines (from the master machine). I have also managed to run a similar program but without the MPI, this involved compiling with gcc and when running putting sudo in front of the binary file. When I combine these two processes I get various error messages. For input: mpiexec -phrase cat -machinefile machinefile -n 2 ~/main the error is: Can't open /dev/mem Did you forget to use 'sudo .. ?' For input: sudo mpiexec -phrase cat -machinefile machinefile -n 2 ~/main the error is: sudo: mpiexec: Command not found I therefore put mpiexec into /usr/bin now for input: sudo mpiexec -phrase cat -machinefile machinefile -n 2 ~/main the error is: Can't open /dev/mem Did you forget to use 'sudo .. ?' Does anyone know how I can work around this? Thanks, Eibhlin