Encrypted cloud backups with Duplicity

Backup Cycles

Because full backups take up so much space, you should consider in advance how often you want to do this. Your setup will depend on how often the data changes and how much space is available, among other things.

The option --full-if-older-than 1M tells Duplicity to create a full backup if the last full backup back is already more than a month old. This step removes the need to write complicated scripts or several cronjobs to switch between full and incremental backups.

For an automated backup, the commands in Listing 1 and a verification routine can be built into a script that a cronjob runs on a regular basis, such as:


If the backup computer is not permanently up, you can use Anacron, which completes the necessary backups even if the computer was not running at the scheduled time.

To delete old backups without manual intervention, you can easily adjust Listing 1. The command

$ duplicity --s3-use-new-style --s3-european-buckets --encrypt-key ${GPG_KEY} remove-older-than 6M --force ${AMAZON_S3}

automatically deletes any backups from Amazon S3 storage that are more than six months old.


  1. Incremental backups vs. full backups: http://lists.gnu.org/archive/html/duplicity-talk/2013-04/msg00041.html
  2. Duplicity front ends: http://duply.net
  3. DateTime according to W3C: http://www.w3.org/TR/NOTE-datetime

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