Hi,
when writing the content for the Tor Relay Guide we also collected steps to enable auto updates for various Linux distributions.
The motivation for this is that there are a lot of relays (>3000) running outdated tor releases.
If more operators enable auto-updates the number of outdated tor relays hopefully decreases.
https://trac.torproject.org/projects/tor/wiki/TorRelayGuide#AutomaticSoftwar...
Debian: https://trac.torproject.org/projects/tor/wiki/TorRelayGuide/DebianUbuntuUpda...
RPM Distros: https://trac.torproject.org/projects/tor/wiki/TorRelayGuide/RPMUpdates
thanks, nusenu