I’m paranoid about backups and I have good reasons for that. I’ve tested many open source tools for automatic backup available for linux, but none of them fulfilled all my requirements.

I liked Déjà-Dup a lot, but it wasn’t able to abort a backup once the destination directory (portable hdd) wasn’t present (or rather: it did abort, but tried to prepare a backup anyway, consuming some cpu on the way). Second thing about Déjà-Dup I didn’t like is that it divides backup files into 5 megabyte archives — opening a directory containing 20 gigabytes of such archives takes a while (I understand the reason for such small volumes is handling Amazon S3, but for local backups it makes no sense), and finally, Déjà-Dup can’t make automatic backups more often than once a day (did I mention I’m a bit paranoid?). However, Déjà-Dup integrates with Gnome very nicely, and since it uses duplicity as a backend, I was able to come up with a simple script fixing all the problems in a couple of minutes.

#!/bin/bash

BACKUP_SCRIPT=${0##*/}
DUPLICITY="/usr/bin/duplicity"
DATE="/bin/date +%R-%d-%m-%y"

BACKUP_COMMAND="$DUPLICITY --exclude=/media/backups --exclude=/home/piotr/.cache --include=/home/piotr --exclude=** --no-encryption / file:///media/backups --volsize=250 --archive-dir=/home/piotr/.cache/deja-dup"

# Sanity checks
if test -z "$BASH" ; then
   printf "$DATE \n$BACKUP_SCRIPT:$LINENO: please run this script with the BASH shell\n" >&2
   exit 192
fi
if test ! -x "$DUPLICITY" ; then
   printf "$DATE \n$BACKUP_SCRIPT:$LINENO: the command $DUPLICITY is not available - aborting\n" >&2
   exit 192
fi

# Create an incremental backup if the portable drive is connected
if test -d /media/backups ; then
    printf "\n\n\n\n\n`$DATE` \nBacking up!\n-------------------------------------------------\n"
    $BACKUP_COMMAND
else
    printf "`$DATE` \n$BACKUP_SCRIPT:$LINENO: portable drive not connected - aborting\n\n" >&2
    exit 192
fi

# Cleanup
printf "`$DATE` Files backed up successfully\n-------------------------------------------------\n"
exit 0   # all is well

The best way is to first configure Déjà-Dup according to your needs, then copy the duplicity command it uses while backing up (it’s visible in STDOUT once you set an environment variable DEJA_DUP_DEBUG=1), paste it into the script, tune it (I’ve changed the volume size), and simply put it to crontab — this way it’s easy to control how often your backups are done.

Feel free to use the script if you need it, and if you’re better in unix scripting than I am (and I believe you are), send me any improvements and/or comments.