Created a medium instances, it showed an error or not getting into the ssh, due to non-availability of ssh port in the security group. some command line tips

• to rename a file or folder mv old_name new_name
• to install git sudo apt-get install git-core
• PostgreSQL reference http://www.thegeekstuff.com/2009/04/15-practical-postgresql-database-adminstration-commands/
• to use FileZilla with AWS http://glidingphenomena.blogspot.in/2011/03/using-filezilla-to-login-into-amazon.html