title: How to fix "no previous regular expression" error when running a 'sed' command?
body: <p>I'm trying to run the following expression in a script to find a device and change one of the fields associated with the device in an HTML file.</p>
  <pre><code>sed -e &quot;s/$OLDTEST/$TESTING/&quot; -e &quot;s/$CURRENTVALU/$NEWSTATUS---$DATE/&quot; -e &quot;s/$PASSORFAIL/$PASSORFAILNEW/&quot; -e &quot;s/$BGCOLOR/$BGCOLORNEW/$POSITION&quot;  -e &quot;s/$OLDNOTE/$NOTE/&quot;  &gt;&gt; //sysadm/shared/file.tmp
  </code></pre>
  <p>I seem to keep getting a &quot;no previous regular expression&quot;. Any ideas?</p>
  <p>debug log output:</p>
  <pre><code>sed -e s//Yes/ -e s//Resolved---03-25-13/ -e s//Pass/ -e s//#348017/1 -e s///
  
  sed: -e expression #5, char 0: no previous regular expression
  </code></pre>