title: Command not found when comparing string
body: <p>I have this script</p>
  
  <pre><code>#!/bin/sh        
  if [ $# -ne 3 ] ; then
              echo "param 1, param2, and A or B "
              exit 1;
  
      elif [ $# -eq 3 ]; then
                      if [$3 = "A"] ; then
                                      echo "A"
                      elif [$3 = "B"]; then
                                      echo "B"
                      fi
  
  fi
  </code></pre>
  
  <p>It is basically checking if param 3 is A or B, and do echo. But it returns: </p>
  
  <pre><code>./test.sh: line 6: [A: command not found
  ./test.sh: line 8: [A: command not found
  </code></pre>
  
  <p>I tried to use <code>-eq</code> for comparison, but it still does not work. How can I fix this problem?</p>