I was running bitcoin on my computer, but when I log out, the bitcoin program stops. Because I wanted to generate coins also when not logged in, I wanted to run the bitcoin daemon. Finally I got around to figure out how.
First I needed to install the bitcoin package 0.3.24-ppa2~maverick
from a ppa https://launchpad.net/~stretch/+archive/bitcoin. Then I had to edit my (already existing) ~/.bitcoin/bitcoin.conf file and add a user and password. Otherwise the daemon wouldn't start up. Then I set gen=1 to generate coins and started the daemon up with
bitcoin -daemon
Then you can test whether it really generates coins with
bitcoin getgenerate