Poppins

Poppins is a command line utility, written in PHP, which takes copies from remote Unix based systems. Optionally it can also backup MySQL databases. The data are stored on a file system, in incremental snapshots. All network transfers are encrypted with SSH.

The backups are incremental forever. After the first copy, only modified data will transfer over the network. Unmodified files are only written to disk once. Old snapshots are automatically deleted according to your own preferences. You could take a backup every day and keep them for a week, plus make a different snapshot every two weeks and keep those for 3 months, for instance.

Poppins can use the snapshot features in ZFS or BTRFS. It is also possible to use a regular file system such as ext4, in which case the snapshots are written in separate directories and the files which have not been modified since the previous backup are saved as hardlinks.

Poppins is a purely command line utility and is configured using one config file per backup you want. A sample file with sensible defaults is included. Use a scheduler like Cron to automate taking regular backups.