curl offers a busload of useful tricks like proxy support, user authentication, ftp upload, HTTP post, SSL (https:) connections, cookies, file transfer resume and more
curl is availabe mostly on all Linux distros but you can download a binary package from cURL's download page if you don't have it installed.
Open the terminal and past the below mentioned command to send the status to the twitter
curl --basic --user username:password --data status="Linux" http://twitter.com/statuses/update.xmlcommand explanation
--basic --user username:password
The above piece of code will authenticate your Twitter username and password.
--data status="Linux"
The above piece of code will send the data to the API i.e your new status which will be in the form of POST HTTP request.
http://twitter.com/statuses/update.xml
The main part of the code which is the URL of the Twitter API.
source:http://linuxpoison.blogspot.com/2010/07/13578167759812.html