title: Ignore spaces, tabs and new line in SED
body: <p>I tried to replace a string in a file that contains tabs and line breaks. 
  the command in the shell file looked something like this:</p>
  
  <pre><code>FILE="/Somewhere"
  STRING_OLD="line 1[ \t\r\n]*line 2"
  sed -i 's/'"$STRING_OLD"'/'"$STRING_NEW"'/' $FILE
  </code></pre>
  
  <p>if I manually remove the line breaks and the tabs and leave only the spaces then I can replace successfully the file. but if I leave the line breaks then <code>SED</code> is unable to locate the <code>$STRING_OLD</code> and unable to replace to the new string</p>
  
  <p>thanks in advance</p>
  
  <p>Kobi</p>