title: Specify directory where gfortran should look for modules
body: <p>I currently compile programs based on modules (such as main program <code>foo</code> which depends on module <code>bar</code>) as follows:</p>
  
  <pre><code>gfortran -c bar.f90
  gfortran -o foo.exe foo.f90 bar.o
  </code></pre>
  
  <p>This works fine when <code>foo.f90</code> and <code>bar.f90</code> are in the same directory.  How do I specify a directory where gfortran should look for <code>bar.o</code> when I call <code>use bar</code> in <code>foo.f90</code>?  (i.e. I don't want to specify that the compiler should link <code>bar.o</code> specifically, I just want it to go find it.)</p>