Remove all previous version MPI and reinstall correctly it
<p>First of all: I'm on linux mint 17.3 x64</p>

<p>What I've done so far:</p>

<ul>
<li><a href="http://sysads.co.uk/2014/05/install-open-mpi-1-8-ubuntu-14-04-13-10/" rel="nofollow">Guide to install Open MPI 1.8</a></li>
<li><a href="https://jetcracker.wordpress.com/2012/03/01/how-to-install-mpi-in-ubuntu/" rel="nofollow">Guide to install MPI</a></li>
<li>Attemp to remove MPI executing: <code>sudo apt-get install libcr-dev mpich2 mpich2-doc</code> (Actually the should be not installed)</li>
</ul>

<p>What I can see from terminal:</p>

<p><strong>output of:</strong> <code>echo $PATH</code></p>

<pre><code>/path/to/mpj//bin:/home/timmy/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/home/timmy/.openmpi/bin
</code></pre>

<p>(I immagine that I've to remove <code>/path/to/mpj/</code> (not exists) and <code>/home/timmy/.openmpi/bin</code> (I want to remove previous version of ompi))</p>

<p><strong>output of:</strong>  <code>echo $LD_LIBRARY_PATH</code></p>

<pre><code>(nothing)
</code></pre>

<p>Really, doesn't appear anything!</p>

<p><strong>output of</strong> <code>mpirun</code></p>

<pre><code>--------------------------------------------------------------------------
mpirun could not find anything to do.

It is possible that you forgot to specify how many processes to run
via the "-np" argument.
--------------------------------------------------------------------------
</code></pre>

<p><strong>Why I want to remove Open MPI and reinstall it</strong></p>

<ul>
<li>I've a project to do using both MPI and OpenMP and with the actual installation of MPI I cannot compile using the following command: <code>mpicc -openmp "test_omp.c" -o "test_omp"</code>. It gives me the following error: <code>Not defined function omp_get_thread_num();</code> and moreover, it ignore my <code>#pragma</code> commands.</li>
</ul>