title: When to use space or tab in Makefile?
body: <p>I am creating a makefile that uses the condition if and ifneq. 
  I noticed that if I am using if, the next lines should be indented by spaces.</p>
  
  <pre><code>if [-d "$$d" ]; then
  &lt;space&gt;&lt;space&gt;&lt;space&gt; echo "file found";
  fi;
  </code></pre>
  
  <p>But if I am using the ifneq command, the next lines had to be indented by tabs.</p>
  
  <pre><code>ifneq ($(strip $(USE_FILE)),NO)
  &lt;tab&gt;echo "file not to be used"
  endif
  </code></pre>
  
  <p>Space and tabs should not matter at all. But how come in makefile, there is a difference with space and tab?</p>