title: Assigning values by doing multiple commands per bash test statement not work
body: <p>When I want to issue multiple command by using bash test statement with subshell, this works:</p>
  <pre><code>a=255
   b=0
   [[ a -eq 255 ]] &amp;&amp; ( echo $a;echo $b )
  255
  0
  </code></pre>
  <p>But why assign values not work?</p>
  <pre><code>[[ a -eq 255 ]] &amp;&amp; ( a=0;b=255 )
   echo $a
  255
  
   echo $b
  0
  </code></pre>
  <p>I know if I change the parenthesis to bracket, it works, and I just want to know why it doesn't work when assigning values.</p>