title: bash file can not cat string after reading line of file
body: <p>I have a list file each line has a format like "0,[0-9]". I write following code in bash file:</p>
  
  <pre><code>while read line 
  do
     grep $line Search.txt
  done &lt; list.txt
  </code></pre>
  
  <p>but I do not get any result as when I write</p>
  
  <pre><code>command="$line Search.txt"
  echo $command
  </code></pre>
  
  <p>I get only</p>
  
  <pre><code>Search.txt
  </code></pre>
  
  <p>and $line becomes NULL.
  What is the problem here with bash or using while for reading file?</p>