Mercurial (software)

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Mercurial
Developed by	Matt Mackall
Latest release	1.0.1 / May 22, 2008
Written in	Python and C
OS	Unix-like, Windows, Mac OS X
Genre	Revision control
License	GPL
Website	http://www.selenic.com/mercurial/

Mercurial is a cross-platform, distributed source management tool for software developers.

It is written in Python, with a binary diff implementation written in C. Mercurial is primarily a command line program. All its commands begin with hg, a reference to the chemical symbol for mercury.

Its major goals include high performance and scalability; serverless, fully distributed collaborative development; robust handling of both plain text and binary files; and advanced branching and merging capabilities, while remaining conceptually simple. It includes an integrated web interface.

The creator and lead developer of Mercurial is Matt Mackall. The full source code is available under the terms of the GNU General Public License, making Mercurial free software.

1 Technical information
2 Documentation
3 History
4 Related software
5 Projects using Mercurial
6 See also
7 References
8 External links

[edit] Technical information

Like Git and Monotone, Mercurial uses SHA-1 hashes to identify revisions.

Mercurial uses an efficient, HTTP-based networking protocol that works to reduce round-trip requests, new connections and data transferred. Mercurial can also work over ssh where the protocol is very similar to the HTTP-based protocol.

Mercurial was written to run on Linux. It has been ported to Windows, Mac OS X, and most other Unix-like systems.

[edit] Documentation

A comprehensive reference manual, Distributed revision control with Mercurial^[1], has been written by Bryan O'Sullivan. The manual is freely available under the terms of the Open Publication License.

[edit] History

Mackall first announced Mercurial on April 19, 2005.^[2] The immediate stimulus for this was the announcement earlier that month by Bitmover that they were withdrawing the free version of BitKeeper.

BitKeeper had been used for the version control requirements of the Linux kernel project till then, but since it could not be so any longer, Mackall decided to write a replacement distributed version control system for use on the Linux kernel. This project started at approximately the same time as another project called Git, started by Linus Torvalds with similar aims.

The Linux kernel went on to use Git rather than Mercurial, but Mercurial is now used by many other projects, see below.

[edit] Related software

Screenshot of hgk in action.

GUI interfaces for Mercurial include Hgk (Tcl/Tk). This is implemented as a Mercurial extension, and is part of the official version. This viewer displays the directed acyclic graph of the changesets of a Mercurial repository. This viewer can be invoked via the command 'hg view', if the extension is enabled. hgk was originally based on a similar tool for git called gitk. There is also a Gtk client named hgview written in pure python.