Parsing e-mail address and URLs from text

Parsing elements such as e-mail addresses and URLs is a common task. Regular expressions make finding these patterns easy.

How to do it...

The regular expression pattern to match an e-mail address is as follows:

    [A-Za-z0-9._]+@[A-Za-z0-9.]+\.[a-zA-Z]{2,4} 

Consider the following example:

$ cat url_email.txt 
    this is a line of text contains,<email> #[email protected].    
    </email> and email address, blog "http://www.google.com",    
    [email protected] dfdfdfdddfdf;[email protected]<br />
    <a href="http://code.google.com"><h1>Heading</h1>

As we are using extended regular expressions (+, for instance), we should use egrep:

$ egrep -o '[A-Za-z0-9._]+@[A-Za-z0-9.]+\.[a-zA-Z]{2,4}'    
    url_email.txt
    [email protected] 
    [email protected] 
    [email protected]

The egrep regex pattern for an HTTP URL is as follows:

http://[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,4}

Consider this example:

$ egrep -o "http://[a-zA...