I installed MongoDB 2.6 on clean installed Ubuntu 15.04:
sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 7F0CEB10
echo 'deb http://downloads-distro.mongodb.org/repo/ubuntu-upstart dist 10gen' | sudo tee /etc/apt/sources.list.d/mongodb.list
sudo apt-get update
sudo apt-get install -y mongodb-org
It finished without any problems. However, when I tried to start it, I got the following error:
$ sudo service mongod start
Failed to start mongod.service: Unit mongod.service failed to load: No such file or directory.
How can I fix this?