Xdelta is a command line tool for

delta encoding Delta encoding is a way of storing or transmitting data in the form of '' differences'' (deltas) between sequential data rather than complete files; more generally this is known as data differencing. Delta encoding is sometimes called delta comp ...

, which stores or transmits the difference (deltas) between sequential data, instead of entire files. This is similar to

diff In computing, the utility diff is a data comparison tool that computes and displays the differences between the contents of files. Unlike edit distance notions used for other purposes, diff is line-oriented rather than character-oriented, but i ...

and patch, except diff computes and shows the difference between two complete files, while patch is primarily designed for human-readable text files; Xdelta is designed for binary files and does not generate human readable output. Xdelta was first released sometime before October 12, 1997 by Joshua MacDonald, who currently maintains the program. The algorithm of xdelta1 was based on the algorithm of

rsync rsync (remote sync) is a utility for transferring and synchronizing files between a computer and a storage drive and across networked computers by comparing the modification times and sizes of files. It is commonly found on Unix-like opera ...

, developed by

Andrew Tridgell Andrew "Tridge" Tridgell (born 28 February 1967) is an Australian computer programmer. He is the author of and a contributor to the Samba (software), Samba file server, and co-inventor of the rsync algorithm. He has analysed complex proprieta ...

, though it uses a smaller block size. Xdelta version 3 is primarily designed to work with streams following the standardized VCDIFF format, and it realized the compatibility among other delta encoding software which supports the VCDIFF format. It runs on

Unix-like A Unix-like (sometimes referred to as UN*X, *nix or *NIX) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Uni ...

operating systems and

Microsoft Windows Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...

. xdelta can handle up to 2⁶⁴ byte files,xdelta3 memory tuning
/ref> and it is suitable for large backups.

References

External links

Project site

Andrew Tridgell's PhD on rsync, with a section on xdelta
(xdelta1)

The VCDIFF Generic Differencing and Compression Data (xdelta3) Free file comparison tools Free software programmed in C Free software programmed in C++ Software using the Apache license {{free-software-stub