AWS EC2 Ubuntu 12.04.1 LTS: deb command-not-found

When I tried to install mongoDb in my AWS EC2 Linux instance:Ubuntu 12.04.1 LTS, deb http://downloads-distro.mongodb.org/repo/ubuntu-upstart dist 10gen I get this following error, meaning deb command is not found. ``` $ deb Sorry, command-not-found has crashed! Please file a bug report at: https://bugs.launchpad.net/command-not-found/+filebug Please include the following information with the report: command-not-found version: 0.2.44 ``` Can someone please help me find out how to install deb in my AWS instance?