title: defining default values in makefile
body: <p>My makefile has line like this       </p>
  
  <pre><code>   CFLAGS = -c -g -D OPT1 -D OPT2
  </code></pre>
  
  <p>I want to pass this arguments through command line like this       </p>
  
  <pre><code> make ARG1= OPT1 ARG2 =OPT2    
  </code></pre>
  
  <p>If I dont pass these arguments through command line I want makefile to use  take default values  defined in makefile. How do I do that ?</p>