We're running unattended-upgrades on debian squeeze, and would like it to run once a week, only on a Wednesday morning. To attempt this, we have set: APT::Periodic::Unattended-Upgrade "7" in /etc/apt/apt.conf.d/50unattended-upgrades And then touched the /var/lib/apt/periodic/update-stamp to set the timestamp to a Wednesday, for instance: touch -t 201211280000 /var/lib/apt/periodic/update-stamp Running: stamp=$(date --date=$(date -r /var/lib/apt/periodic/update-stamp --iso-8601) +%s 2/dev/null) date -u --date="1970-01-01 $stamp sec GMT" Gives the correct timestamp: Wed Nov 28 00:00:00 UTC 2012 However, unattended-upgrades then seems to ignore this, and run the updates on a Saturday morning. Could anyone enlighten me as to how this parameter works, and how to set up upgrades to run on a Wednesday?