Editing Rsync (section)

== Variations ==
The '''{{visible anchor|rdiff}}''' utility uses the rsync algorithm to generate [[Delta encoding|delta file]]s with the difference from file A to file B (like the utility [[diff]], but in a different delta format). The delta file can then be applied to file A, turning it into file B (similar to the [[patch (Unix)|patch]] utility). rdiff works well with [[binary file]]s.

The '''[[rdiff-backup]]''' script maintains a [[backup]] mirror of a file or directory either locally or remotely over the network on another server. rdiff-backup stores incremental rdiff deltas with the backup, with which it is possible to recreate any backup point.<ref>{{official website
 | 2 = rdiff-backup
 | 1 = rdiff-backup.net/
}}</ref>

The '''librsync''' library used by rdiff is an independent implementation of the rsync algorithm. It does not use the rsync network protocol and does not share any code with the rsync application.<ref name="pool">Pool, Martin; [http://librsync.sourcefrog.net/ "librsync"] {{Webarchive|url=https://web.archive.org/web/20131209003912/http://librsync.sourcefrog.net/ |date=9 December 2013 }}</ref> It is used by [[Dropbox (service)|Dropbox]], rdiff-backup, [[duplicity (software)|duplicity]], and other utilities.<ref name="pool" />

The '''acrosync''' library is an independent, cross-platform implementation of the rsync network protocol.<ref>{{Cite web |last=Chen |first=Gilbert |title=acrosync-library |url=https://github.com/gilbertchen/acrosync-library |url-status=live |archive-url=https://web.archive.org/web/20170210051004/https://github.com/gilbertchen/acrosync-library |archive-date=10 February 2017 |access-date=22 June 2016 |publisher=github.com}}</ref>  Unlike librsync, it is wire-compatible with rsync (protocol version 29 or 30). It is released under the [[Reciprocal Public License]] and used by the commercial rsync software '''Acrosync'''.<ref>{{Cite web |title=acrosync.com |url=https://acrosync.com |url-status=live |archive-url=https://web.archive.org/web/20191220113527/http://acrosync.com/ |archive-date=20 December 2019 |access-date=29 July 2020}}</ref>

The '''[[Duplicity (software)|duplicity]]''' backup software written in '''[[Python (programming_language)|python]]''' allows for incremental backups with simple storage backend services like local file system, [[SSH File Transfer Protocol|sftp]], [[Amazon S3]] and many others. It utilizes librsync to generate delta data against signatures of the previous file versions, encrypting them using [[GNU Privacy Guard|gpg]], and storing them on the backend. For performance reasons a local archive-dir is used to cache backup chain signatures, but can be re-downloaded from the backend if needed.

As of macOS 10.5 and later, there is a special <code>-E</code> or <code>--extended-attributes</code> switch which allows retaining much of the [[HFS Plus|HFS+]] file metadata when syncing between two machines supporting this feature. This is achieved by transmitting the [[Resource Fork]] along with the Data Fork.<ref>{{Cite web |title=Mac Developer Library |url=https://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/man1/rsync.1.html |url-status=dead |archive-url=https://web.archive.org/web/20120926232217/http://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/man1/rsync.1.html |archive-date=26 September 2012 |access-date=18 August 2014 |publisher=Developer.apple.com}}</ref>

'''zsync''' is an rsync-like tool optimized for many downloads per file version. zsync is used by Linux distributions such as [[Ubuntu (operating system)|Ubuntu]]<ref>{{Cite web |title=Zsync Cd Image |url=https://help.ubuntu.com/community/ZsyncCdImage |access-date=6 January 2015 |website=ubuntu.com}}</ref> for distributing fast changing beta [[ISO image]] files. zsync uses the HTTP protocol and .zsync files with pre-calculated rolling hash to minimize server load yet permit diff transfer for network optimization.<ref>[http://zsync.moria.org.uk zsync web site]</ref>

'''[[Rclone]]''' is an open-source tool inspired by rsync that focuses on cloud and other high latency storage. It supports more than 50 different providers and provides an rsync-like interface for cloud storage.<ref>{{Cite web |last=Craig-Wood |first=Nick |title=Overview of cloud storage systems |url=https://rclone.org/overview/ |url-status=live |archive-url=https://web.archive.org/web/20171004030724/https://rclone.org/overview/ |archive-date=4 October 2017 |access-date=10 July 2017 |website=rclone.org}}</ref> However, Rclone does not support rolling checksums for partial file syncing (binary diffs) because cloud storage providers do not usually offer the feature and Rclone avoids storing additional metadata.<ref>{{Cite web |last=Craig-Wood |first=Nick |title=Rclone Frequently Asked Questions |url=https://rclone.org/faq/#why-doesn-t-rclone-support-partial-transfers-binary-diffs-like-rsync |url-status=live |archive-url=https://web.archive.org/web/20220510195418/https://rclone.org/faq/ |archive-date=10 May 2022 |access-date=13 May 2022 |website=rclone.org}}</ref>