title: "test: argument expected " met when test a file using "-e" option
body: <p>When executing following code segment, error "test: argument expected" always occurs. However, if I change "-e" to "-s", this error will disappear. Is it possible to eliminate this error but keep "-e" unchanged?</p>
  
  <pre><code>OAMPROXY_BKOUT_SPF="/var/ap/platform/rccCfgBkup/backout.spf"
  if [ -e ${OAMPROXY_BKOUT_SPF} ] &amp;&amp; [ "${IS_GENERIC_RETROFIT}" = "no" ]
  then
      # Do something here
  fi
  </code></pre>
  
  <p>Thank you very much!</p>