[ubuntu-nz] How to mount USB drive when no-one is logged in?

[Johann Schoonees]

I've googled and searched the archives but I'm getting swamped with 
marginally related "USB drive does not mount" hits.  Here goes:

When I log into the kubuntu Feisty desktop, there is an icon showing 
that my external USB drive is connected and mounted.

However, cron runs a nightly back-up script for me at 3 am when no-one 
should be logged in, but after migrating from Fedora to Feisty, it fails 
at the point where I try to mount the external USB drive:

MOUNT_OK=no
for DISK in $DISK_LABELS
do
# mount -w "$MOUNT_POINT/$DISK" 2> /dev/null
mount -w "$MOUNT_POINT/$DISK"
MOUNT_RES=$?
if [ "$MOUNT_RES" = "0" ]; then
MOUNT_OK=yes
break
fi
done

results in:

mount: can't find /media/backup_0 in /etc/fstab or /etc/mtab
mount: can't find /media/backup_1 in /etc/fstab or /etc/mtab
mount: can't find /media/backup_2 in /etc/fstab or /etc/mtab
...

even when a disk with label backup_1 (or 2 etc.) is connected.

There is no entry for /dev/sdb1 in /etc/fstab.  There is one in etc/mtab 
when someone is logged into the desktop, but not when not.  It looks 
something like this:

/dev/sdb1 /media/backup_1 ext3 rw,noexec,nosuid,nodev,sync,data=ordered 0 0

Under Fedora it used to look like this:

/dev/sdb1 /media/backup_1 ext3 rw,nosuid,nodev 0 0

The exact mount point depends on the disk label.  I have more than one 
back-up disk, each with a unique label.

Under Fedora there used to be an entry in fstab like this:

/dev/sdb1 /media/backup_1 ext3 pamconsole,exec,noauto,managed 0 0

which changed automatically (apparently under control of something 
called fstab-sync which I don't see in kubuntu) according to the label 
of the connected drive.

In short, how should my script detect and mount a connected USB external 
drive when no-one is logged in?

Any help appreciated,
Johann