GNU Hurd

What is the Hurd?

The GNU Hurd is the GNU project's replacement for the Unix kernel. The Hurd is a collection of servers that run on the Mach microkernel to implement file systems, network protocols, file access control, and other features that are implemented by the Unix kernel or similar kernels (such as Linux).

Currently, the Hurd runs on i386 machines. The Hurd should, and probably will, be ported to other hardware architectures or other microkernels in the future.

Advantages of the Hurd

The Hurd is not the most advanced operating system known to the planet (yet), but it does have a number of enticing features:

it's free software: Anybody can use, modify, and redistribute it under the terms of the GNU General Public License (GPL). The Hurd is part of the GNU system, which is a complete operating system licensed under the GPL.
it's compatible: The Hurd provides a familiar programming and user environment. For all intents and purposes, the Hurd is a modern Unix-like kernel. The Hurd uses the GNU C Library, whose development closely tracks standards such as ANSI/ISO, BSD, POSIX, Single Unix, SVID, and X/Open.
it is built to survive: Unlike other popular kernel software, the Hurd has an object-oriented structure that allows it to evolve without compromising its design. This structure will help the Hurd undergo major redesign and modifications without having to be entirely rewritten.
it's scalable: The Hurd implementation is aggressively multithreaded so that it runs efficiently on both single processors and symmetric multiprocessors. The Hurd interfaces are designed to allow transparent network clusters (collectives), although this feature has not yet been implemented.
it's extensible: The Hurd is an attractive platform for learning how to become a kernel hacker or for implementing new ideas in kernel technology. Every part of the system is designed to be modified and extended.
it's stable: It is possible to develop and test new Hurd kernel components without rebooting the machine (not even accidentally). Running your own kernel components doesn't interfere with other users, and so no special system privileges are required. The mechanism for kernel extensions is secure by design: it is impossible to impose your changes upon other users unless they authorize them or you are the system administrator.
it exists: The Hurd is real software that works Right Now. It is not a research project or a proposal. You don't have to wait at all before you can start using and developing it.

What the name ``Hurd'' means

According to Thomas Bushnell, BSG, the primary architect of the Hurd, ```Hurd' stands for `Hird of Unix-Replacing Daemons'. And, then, `Hird' stands for `Hurd of Interfaces Representing Depth'. We have here, to my knowledge, the first software to be named by a pair of mutually recursive acronyms.''

Status of the project

The last official release was the 0.2 binary distribution of June 1997. At the moment, the Hurd developers and people from the Debian Project are assembling a new distribution; it will become the 0.3 distribution.

The new distribution will use the Debian package management system to ease installation and updating the system. This package management system is the same one used in Debian GNU/Linux distributions. In parallel to the Linux distribution, the upcoming Hurd distribution will be called Debian GNU/Hurd.

These efforts are ongoing, but the fundamental packages are ready and quite stable. If you want to try out the Hurd, it is recommended that you use the preliminary 0.3 version instead of the 0.2 version, because the newer snapshots have many bugs fixed and are more stable.

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Updated: 23 Jan 1999 matthias