Free librsync software for linux

librsync is a free software library that implements the rsync remote-delta algorithm. This algorithm allows efficient remote updates of a file, without requiring the old and new versions to both be present at the sending end.

The library uses a "streaming" design similar to that of zlib with the aim of allowing it to be embedded into many different applications.

librsync is currently pre-1.0, with most important functionality working.

librsync is not wire-compatible with rsync 2.x, and is not likely to be in the future.

This is a new codebase, designed to allow a fresh start on the problem and a cleaner design. It may be used in a future version of rsync or a successor project. Early steps towards that are visible in Waynes rZync prototype, and Martins superlifter design.

The librsync project was created by Martin Pool and is now being enhanced and finished by the folks you can find on the project page.

The librsync algorithm is based on the well-known and trustworthy rsync software by Andrew Tridgell.

Duplicity backs directories by producing encrypted tar-format volumes and uploading them to a remote or local file server.
Because duplicity uses librsync, the incremental archives are space efficient and only record the parts of files that have changed since the last backup. Because duplicity uses GnuPG to encrypt and/or sign these archives, they will be safe from spying and/or modification by the server.
The duplicity package also includes the rdiffdir utility. Rdiffdir is an extension of librsyncs rdiff to directories---it can be used to produce signatures and deltas of directories as well as regular files. These signatures and deltas are in GNU tar format.
Main features:
Easy to use: Although duplicity is a command-line utility, the semantics are relative simply. To take a basic example, this command:
- duplicity /usr scp://host.net/target_dir
- backs up the /usr directory to the remost host host.net via scp.
Encrypted and signed archives: The archives that duplicity produces can be encrypted and signed using GnuPG, the standard for free software cryptology. The remote location will not be able to infer much about the backups other than their size and when they are uploaded. Also, if the archives are modified on the remote side, this will be detected when restoring.
Bandwidth and space efficient: Duplicity uses the rsync algorithm so only the changed parts of files are sent to the archive when doing an incremental backup. For instance, if a long log file increases by just a few lines of text, a small diff will be sent to and saved in the archive. Other backup programs may save a complete copy of the file.
Standard file format: Athough archive data will be encrypted, inside it is in standard GNU-tar format archives. A full backup contains normal tarballs, and incremental backups are tar archives of new files and the deltas from previous backups. The deltas are in the format produced by librsyncs command-line utility rdiff.
- Although you should never have to look at a duplicity archive manually, if the need should arise they can be produced and processed using GnuPG, rdiff, and tar.
Choice of remote protocol: Duplicity does not make many demands on its archive server. As long as files can be saved to, read from, listed, and deleted from a location, that location can be used as a duplicity backend. Besides increasing choice for the user, it can make a server more secure, as clients only require minimal access.
- Currently local file storage, scp/ssh, ftp, rsync, and Amazon S3 are supported, and others shouldnt be difficult to add.