Linux at my work

edit /etc/passwd file and change shell (you need to login as root user):

# vi /etc/passwd

Last filed is shell
From
vivek:x:1000:1000:vivek,,,:/home/vivek:/bin/sh
To
vivek:x:1000:1000:vivek,,,:/home/vivek:/usr/local/bin/bash

Save and close the file.

link - http://www.cyberciti.biz/faq/howto-set-bash-as-your-default-shell/