title: Using grep to find all emails
body: <p>How to properly construct regular expression for "grep" linux program, to find all email in, say /etc directory ?
  Currently, my script is following:</p>
  
  <pre><code>grep -srhw "[[:alnum:]]*@[[:alnum:]]*" /etc
  </code></pre>
  
  <p>It working OK - a see some of the emails, but when i modify it, to catch the one-or-more charactes before- and after the "@" sign ...</p>
  
  <pre><code>grep -srhw "[[:alnum:]]+@[[:alnum:]]+" /etc
  </code></pre>
  
  <p>.. it stops working at all</p>
  
  <p>Also, it does't catches emails of form "Name.LastName@site.com"</p>
  
  <p>Help !</p>