Installing open MPI and/or executing hello_c/ring_

问题:

I am trying to install open MPI version 1.6.5 on a freshly installed Ubuntu 14.04 LTS. I do it as described here and here. For the installation I use following commands:

1. Install C/C++ Compiler and openmpi-bin: root#: apt-get install build-essential openmpi-bin
2. Download and unpack: root#: wget https://www.open-mpi.org/software/ompi/v1.6/downloads/openmpi-1.6.5.tar.gz root#: tar -xf openmpi-1.6.5.tar.gz -C /opt root#: chown root:root /opt/openmpi-1.6.5
3. Configure installation file and install it: root#: cd /opt/openmpi-1.6.5 root#: ./configure --prefix=/opt/openmpi root#: make all install
4. Export Environment Variables: export PATH=$PATH:/opt/openmpi/bin export LD_LIBRARY_PATH=/opt/openmpi/lib

IMO I didn't miss any of the installation steps. But when I try to run the usual tests on the local host (i.e. 'zeus' in my case) i get following results:

1. root#: mpirun hostname Outputs the right hostname, in my case 'zeus'

2. root#: mpirun hello_c

   --------------------------------------------------------------------------
   mpirun was unable to launch the specified application as it could not find an executable:
   
   Executable: hello_c
   Node: zeus
   
   while attempting to start process rank 0.
   --------------------------------------------------------------------------
   

3. Same for root#: mpirun ring_c

What did I miss?