Automate data backup at the command line

Manual Trigger

An increasing number of incremental backups accumulates over time, especially if you automate the backup runs. Because these need to be restored in sequence from the last full backup, it is a very good idea to create a new full backup regularly to minimize the number of incrementally backed up archives. Duplicity launches into a full manual backup when started with the full parameter. The incremental parameter manually triggers an incremental backup.

If specific directories are to be excluded from the backup, you can specify these using the --exclude parameter. Several directories that you do not want backed up can be added in a space-separated list. Excluding individual directories is useful, especially for subfolders that contain, for example, temporary, cache, or logfiles.

However, caution is required when backing up the root directory: The /proc directory must be excluded; otherwise, Duplicity will freeze. Conversely, the --include parameter can include additional folders in the backup.

Restore

Data recovery is just as easy: Duplicity is activated without any additional parameters; only the source and target paths need to be swapped. Alternatively, you can also specify a different target path. The archive is only unpacked after entering the passphrase, so unauthorized persons cannot access the data without knowing the password.

Using the verify and --compare-data parameters, you can test the integrity of your backups in a simple way. This test is possible even if the volumes are in a cloud. Particularly for documentation purposes, it is recommended to use the additional -v<x> parameter (verbosity level), and to replace the x placeholder with one of the numbers 4, 8, or 9 to obtain meaningful information. The data can then be saved in the specified file using the --log-file <file name> parameter.

rdiff-backup

Rdiff-backup [8] is another popular tool for backing up at the command line. The program is maintained in the repositories of virtually all major Linux distributions. The software is extremely easy to use: To produce a local backup of a directory or directory tree at the prompt, type:

rdiff-backup <Source-Directory> <Target-Directory>

This creates a full backup that the administrator can recover without special tools just as easily as using a conventional folder hierarchy, using only on-board Linux tools.

Subsequently backups made by rdiff-backup contain deleted or older versions of the changed files. The latest versions of the changed files all end up in the full backup, just like new files, so you always have the current status of the backup. Regular backups only save older versions of the database. The advantage of this special form of incremental backup, known as reverse delta, is that you do not have to fight your way through several incremental backups to restore a complete database.

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