The Unleashed Operating System

Unleashed is an operating system fork of illumos, which itself is a derivative of OpenSolaris and therefore has its roots in UNIX System V Release 4.

It is intended as an operating system for developers by developers.

Unleashed is a fork of illumos; it comes with ZFS, DTrace, Crossbow and more.


We try to make Unleashed an operating system that we would like to use.

Our most important goals are:

  1. The contribution process must be simple and must encourage new contributors to repeatedly contribute.
  2. We aim to have periodic releases (roughly one every 6 months). Security patches will be provided between releases.
  3. Unleashed aims to be a modern operating system base.
    1. Modern compiler support. Currently, the base system can only be built with gcc 4.4.4, however we hope to allow a wider range of gcc versions. Eventually, we would like to be able to use clang as well.
    2. The UNIX environment has changed drastically over the past 20 years. As a result, we hope to ship an environment that provides the comforts of modern UNIX, yet maintains the unique features we inherited that set us apart from other UNIX systems out there.
    3. POSIX has won. Therefore, when it does not hinder usability (see item 3.2), we want a system that is POSIX-compliant without having to jump through special hoops (e.g., setting $PATH, or providing extra compiler flags).
    4. We do not support “extreme legacy”. While support for legacy interfaces and binaries is important, it must be done in moderation. Therefore, old interfaces may be removed from time to time. Interface deprecation will be clearly communicated through release notes.
  4. Maintaining code is hard enough when the code is squeaky clean. To make our job easier, we try to get the code clean when first committing it — even if it delays the commit a little bit. In other words, we care about more than just that the code works — we want code we can (for the most part) be proud of.

Download & Installation

The only systems currently supported are amd64-based computers and virtual machines.

Please note that Unleashed is currently not ready for use in a production environment. While we do try to keep up with patches for security vulnerabilities, we do not have enough resources to make any guarantees.

If you wish to build the current master, use the latest available development snapshot.

dev snapshot: latestvarious   [usb] [iso] [p5p] [checksums]
release: 1.02018-06-26 [relnotes] [usb] [iso] [p5p] [checksums]
previous rc: 1.0-rc12018-02-12       [p5p] [checksums]

IRC & Mailing Lists

You can find us in #unleashed on Freenode.

We have two mailing lists: one for general development discussions (subscribe, archives) and one with commit notifications (subscribe, archives).

Security sensitive information can be sent to If you wish, you may encrypt your message with PGP (key ID 0x18F90BEB645EB36FE31AEE9F8311B7D703B1E6C8).


We try to make contributing to Unleashed a straightforward affair. If you have a project in mind or are looking for some suggestions, contact us on IRC or on the mailing list. (A good way to come up with a project is to install and use Unleashed. Anything broken or annoying that you find is a possible project!)

The source code itself is split across several git repositories:

The steps to build each vary, but they are documented in each repository's top-level README.


Aside from the typical set of man pages, there is a docs directory in the main git repository.