Parsing e-mail addresses and URLs from text

Parsing a required text from a given file is a common task that we encounter in text processing. Items such as, e-mails and URLs can be found out with the help of correct regex sequences. Mostly, we need to parse e-mail addresses from a contact list of an e-mail client, which is composed of many unwanted characters and words, or from an HTML web page.

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}

For example:

$ cat url_email.txt 
this is a line of text contains,<email> #[e-mail]. </email> and email address, blog "http://www.google.com", [e-mail] dfdfdfdddfdf;[e-mail]<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
[e-mail] 
test@yahoo...