Con este pequeño script haremos una copia de /home a /media/Backup utilizando rsync, sólo si existe /media/Backup:
#!/bin/sh
carpeta="/media/Backup"
sleep 30
if [ -d $carpeta ]
then
date > /var/log/backup.log
rsync -av --delete --prune-empty-dirs /home $carpeta >> /var/log/backup.log
else
date >> /var/log/backup.log
echo [...]
