Automatically read last backup date

Question

I've noticed that whether or not the Time Machine volume is mounted, the icon in the menu bar displays the last backup date. Is there any way I can read this data from the command line? I found the excellent tms utility (http://fernlightning.com/doku.php?id=software:misc:tms) but it seems to only give the date of last backup if the volume is mounted.
I'm trying to create a simple script that notifies (via email) me if someone in my office hasn't backed up with Time Machine in over X days. Any help would be much appreciated.

Answer 1

I'm not sure where it's recorded on the disk when the TM drive is unmounted but you can see it in system log. so if you grep through the log you'll find the record of the last backup. to see just the date the following will do for example
cat /private/var/log/system.log |grep backup |tail -1 | awk '{print $1" " $2" "$3}'
However, those logs are periodically recycled and if you don't back up in a while this info will be gone from the current system log and the command will return an empty output. you'd have to deal with that somehow. you could for example run the command periodically with a launch daemon and and store the outcome in a file so long as the outcome is not empty.