The Sortix Operating System
===========================
Sortix is a hobby operating system. It was originally created as a tool to learn
more about kernel and operating system design and implementation. Today is
transforming into a real operating system. The standard library and kernel is
rich enough that some third party software can and has been ported to Sortix.
However, the system remains quite limited as of this writing. Many features are
missing such as proper filesystem support, bitmap graphics, and networking.
Proper filesystem support is currently being added.

The system aims to be an Unix-clone and is heavily based on POSIX. However, I've
drawn much inspiration from systems such as Plan 9, GNU/Hurd and MINIX. Indeed,
I plan to construct a micro-kernel with user-space filesystems, per-process
namespaces, replacing many system calls with filesystem nodes, and other
exciting features.

System Requirements
-------------------
Sortix has very low system requirements. It also works well under virtual
machines such as VirtualBox and Qemu.

* A 32-bit x86 or 64-bit x86_64 CPU.
* A dozen megabyte RAM.
* A harddisk or cdrom drive or support for booting from USB.
* A multiboot compliant bootloader if booting from harddisk.
* A Parallel ATA harddisk, if you wish to access it from Sortix. SATA is not
  supported yet.

Features
--------
The current development version of Sortix offers a traditional multi-process
protected environment with round-robin scheduling. A quick and dirty shell is
able to execute programs in foreground or background mode, handle IO redirection
and piping the standard output of a process into the standard input of another.
A real shell will be added as the system matures and I get around to finish the
work in progress shell.

A number of standard utilities are present such as cat, head, tail, clear, cp,
column, kill, ls, rm, pwd, uname, echo, and uptime. There is even a number of 
non-standard utilities such as calc, help, init, kernelinfo, memstat, and pager.
This collection of utilities will continue to grow as it matures and third party
software is ported. I've currently had some luck porting gzip and parts of
binutils.

A number of small games is present and uses the VGA textmode to render ASCII
graphics. Notably you can play two-player Pong, or single-player Snake, or the
nice and turing-complete Conway's Game of Life. These are probably the main
attraction of the system for non-technical people.

The Sortix kernel has very basic filesystem support. The root filesystem / is
simply a single-directory RAM filesystem. The init ramdisk is mounted read-only
on /bin and various devices are accessable through the /dev filesystem. A lot of
work is currently going into implementing a fully-working kernel virtual file
system able to outsource filesystem requests to user-space servers. Once this is
completed we will be able to shape Sortix into a real microkernel based system.

Job control and Unix signals is not fully or correctly implemented. This means
that sequences such as Ctrl-C (SIGINT) not always works correctly. This will
be implemented soon enough (depends partially on VFS; see above).

There currently is no concept of users in the system (only the root user
exists). I decided to delay making a multi-user system until the base system is
in place. Note that there is only a single terminal - even though the system is
a multi-process system, there is only a single /dev/vga and there is no
framework in place for sharing it.

Technical details
----------------
The system is mostly coded in C++, but also contains a few files in C. However,
the user-land experiences a normal C programming interface as per POSIX.
Executable files natively uses the ELF format used on GNU/Linux and other
systems. There is no shared library support yet, but it'll be possible when I
get around to implement copy-on-write memory, mmap(2) and swapping to disk.

Building
--------
To build the Sortix source code you need to install a few dependencies. First of
all you need the GNU Compiler Collection (C and C++), GNU Make, and GNU
Binutils. You then need to build and install the included macro preprocessor
mxmpp somewhere in your PATH such as /usr/bin. If you wish to build the 32-bit
version of Sortix, you need the Netwide Assembler (nasm) as parts of it hasn't
been ported to the GNU assembler yet. You need a GNU/Linux build system to build
Sortix, although, it wouldn't be difficult to port the build system to other
platforms. You can then build the Sortix kernel and user-space utilities by
running make in the Sortix root source directory. By default it will build to
your CPU architecture (64-bit on 64-bit systems, 32-bit otherwise). Use
CPU=x86 or CPU=x64 as arguments to make to control which target is built.

To build a bootable ISO you need GNU GRUB 2, as that is used by "make iso" to
generate the iso. In turn, GNU GRUB relies on xorriso to create the iso file.

You can burn the ISO to a cdrom or dvd, or even dd(1) it onto a USB memory stick
and boot from if it your BIOS supports it. You can also provide it to a virtual
machine. Alternatively you can install the kernel binary and initrd in your
/boot directory and configure GRUB to boot Sortix.

Links
-----
You can visit the official website at http://www.maxsi.org/software/sortix/ for
more information and news. You can also download the newest release and cutting
edge nightly builds.

You can retrieve the current git master from our gitorious project page from
https://gitorious.org/sortix/.

License
-------

Copyright(C) Jonas 'Sortie' Termansen <sortie@maxsi.org> and contributors 2011,
2012.

The Sortix kernel, the filesystem servers, the initrd tools, the utilities, the
games, and the benchmark programs are licensed under the GNU General Public
License, either version 3 or (at your option) any later version.

The libmaxsi standard library is licensed under the GNU Lesser General Public
License, either version 3 or (at your option) any later version.

Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE. See the gpl.html and lgpl.html files for more information.