title: Directory as a dependency in make rule
body: <p>Is it possible to specify a directory as a dependency in a Makefile rule? Actually I have a Makefile in a directory and another directory containing all the source files.</p>
  
  <pre><code>.
  .
  |_ Makefile
  |_ src
      |_a.c
      |_a.h
  </code></pre>
  
  <p>Now I want that whenever I make any change in the src directory i.e. in either of a.c or a.h , a particular rule in my Makefile get called on issuing make command. Something like </p>
  
  <pre><code>Makefile
  .
  .
  .
  build: src
      &lt;commands&gt;
  
  clean:
      &lt;commands&gt;
  </code></pre>