title: [: -eq: unary operator expected
body: <pre><code>#!/bin/bash    
  export PROCNAME=test
  export TABLE_ID=0
  
  if [ ${TABLE_ID} -eq "" ]; then
          echo hello
  fi
  </code></pre>
  
  <p>above throws error:</p>
  
  <blockquote>
    <p>[: -eq: unary operator expected</p>
  </blockquote>
  
  <p>How to fix this with out double square brackets  <code>[[ ${TABLE_ID} -eq "" ]]</code>.</p>