rsync and USB

Because my external USB drive has differing paths, seemingly arbitrary, when it is plugged in I've had to change the commands for my backup.sh. It now says -

if [ -d /media/disk/ ]; then
 /usr/bin/rsync -av /home/boztu/ /media/disk/`/bin/date +%Y%m%d`/ \ >> /home/boztu/cron/backup.txt
 fi
 if [ -d /media/usb/ ]; then
 /usr/bin/rsync -av /home/boztu/ /media/usb/`/bin/date +%Y%m%d`/ \ >> /home/boztu/cron/backup.txt
 fi

So I'm now testing it to see if it works as per the script, but the acid test will be when I reboot, we'll see for definite then.