title: when is double parenthesis construct for conditional statements useful?
body: <p>I've been reading the <a href="http://tldp.org/LDP/abs/html/" rel="nofollow noreferrer" title="Advanced Bash Scripting Guide">Advanced Bash Scripting Guide</a> trying to learn more about what is considered best practice and came across this way of constructing conditionals:</p>
  
  <pre><code>#condition?result-if-true:result-if-false
  
  (( var0 = var1&lt;98?9:21 ))
  #                ^ ^
  
  # if [ "$var1" -lt 98 ]
  # then
  #   var0=9
  # else
  #   var0=21
  # fi
  </code></pre>
  
  <p>It looks cool but is there an advantage to this outside of how compact it is?</p>