I've figured out a way of doing this, it's a bit of a hack using shell scripts, cron and sudo, but it seems to work pretty well.
First, create a shell script
/bin/usertimeout owned by root, chmod it to 755, and paste the following content into the file
# Timeout is the number of seconds a login session can be idle before it is
# automatically logged out.
if [ $(stat -f %u /dev/console) == $UID ]
if [ -e /tmp/backgroundUserLogout.$UID ]
if [ ! -e /tmp/backgroundUserLogout.$UID ]
if [ $(( `date +%s` - `stat -f %m /tmp/backgroundUserLogout.$UID || printf 0` )) -ge $(( $timeout )) ]
Next, create a file
/sbin/killuser, owned by root, chmod it to 755 and paste in the following content
# Logs out the user calling this script
# Get the PID of the loginwindow process for the user executing this
pid=`ps -Axjc | grep ^$SUDO_USER | grep loginwindow | cut -c 14-20 | tr -d /\ /`
# If the PID appears to be valid, kill the process
if [ $pid -gt 0 2>/dev/null ]
kill -9 $pid
Next add a crontab entry for each user that you want to be auto logged out. This would be a pain if you wanted all users to be affected, but in my case, I only require a small number of users to be logged out on idle.
# Crontab for user that has to be autologged out
* * * * * /bin/usertimeout
Note that the example above runs every minute, depending on the idle time you allow, you might want to increase this to a more suitable frequency (e.g. every 15 mins using
*/15 * * * * /bin/usertimeout)
Now a simple mod to the sudoers file using
visudo and you're good to go.
%users ALL=(ALL) NOPASSWD: /sbin/killuser