Newsgroups: comp.os.plan9,comp.os.misc,comp.answers,news.answers From: firstname.lastname@example.org (Steve Kotsopoulos) Subject: Plan 9 from Bell Labs - Frequently Asked Questions [FAQ] Summary: FAQ for the Plan 9 operating system Approved: email@example.com firstname.lastname@example.org Reply-To: email@example.com Organization: FYWSS Expires: Apr 1, 2002 Followup-To: poster Archive-name: comp-os/plan9-faq Last-modified: Mar 3, 2002 Posting-Frequency: monthly URL: http://www.fywss.com/plan9/plan9faq.html
This document answers frequently asked questions about the third edition of the Plan 9 operating system. Much of it was rendered obsolete with the April/2002 release of Plan9 4th Edition, but it is being saved as a reference. It is unlikely to be updated anymore.
For up-to-date information, see http://www.fywss.com/plan9/plan9faq.html.
The following sections are new or modified recently:
A hypertext version of this FAQ is available on my Plan 9 web page, URL http://www.fywss.com/plan9/
Other sources of information include the newsgroup comp.os.plan9, which is bidirectionally gatewayed to the 9fans mailing list (browse archives at https://lists.cse.psu.edu/archives/9fans/ and http://bio.cse.psu.edu/~schwartz/9fans/, or mail firstname.lastname@example.org to subscribe) and of course the Plan 9 homepage at Bell Labs, URL http://plan9.bell-labs.com/plan9dist/
If you'd like to discuss the Plan9 license, send mail to email@example.com. Mailing to this list subscribes you to the list.
Please forward any comments or suggestions regarding this FAQ to
Plan 9 is a new computer operating system and associated utilities. It was built by the Computing Science Research Center of Lucent Technologies Bell Laboratories, the same group that developed Unix, C, and C++.
Plan 9 is a distributed system. In the most general configuration, it
uses three kinds of components: terminals that sit on users' desks,
file servers that store permanent data, and other servers that provide
faster CPUs, user authentication, and network gateways. These components are
connected by various kinds of networks, including Ethernet,
specially-built fiber networks, ordinary modem connections, and ISDN.
In typical use, users interact with applications that run either on
their terminals or on CPU servers, and the applications get their data
from the file servers. The design, however, is highly configurable;
it escapes from specific models of networked workstations and
central machine service.
Subject: What is in the latest Plan9 release?
The press release for the third edition of Plan9 is at http://www.bell-labs.com/news/2000/june/7/2.html
Among the changes in this release of Plan 9 are a revised kernel, which now has the means to resolve ambiguous file names; an improved graphics environment; an updated command set; and expanded libraries. The system's creators also have installed "plumbing," a new mechanism for passing messages between interactive programs, as part of the user interface.
The new release is available for free download under an open source agreement. This is a significant step over previous releases.
If you'd like to browse the distribution packages before actually installing,
you'll need the tools available at
Subject: For History Buffs
The first edition of Plan 9 was released in 1993, and was only available to universities.
In 1995 the second edition was available for purchase under a shrink-wrap license.
The second edition version of this FAQ is archived at
Subject: What is its relation to other operating systems?
Plan 9 is itself an operating system; it doesn't run as an
application under another system. It was written from the ground up
and doesn't include other people's code. Although the
OS's interface to applications is strongly influenced by the approach
of Unix, it's not a replacement for Unix; it is a new design.
Subject: What are its key ideas?
Plan 9 exploits, as far as possible, three basic technical ideas:
first, all the system objects present themselves as named files that
are manipulated by read/write operations; second, all these files
may exist either locally or remotely, and respond to a standard protocol;
third, the file system name space - the set of objects visible to a
program - is dynamically and individually adjustable for each of the
programs running on a particular machine. The first two of these
ideas were foreshadowed in Unix and to a lesser extent in
other systems, while the third is new: it allows a new engineering
solution to the problems of distributed computing and graphics. Plan
9's approach means that application programs don't need to know where
they are running; where, and on what kind of machine, to run
a Plan 9 program is an economic decision that doesn't affect the
construction of the application itself.
Subject: What are the advantages to this approach?
Plan 9's approach improves generality and modularity of application design by encouraging servers that make any kind of information appear to users and to applications just like collections of ordinary files. Here are a few examples.
The Plan 9 window system (called rio) is small and clean in part because its design is centered on providing a virtual keyboard, mouse, and screen to each of the applications running under it, while using the real keyboard, mouse, and screen supplied by the operating system. That is - besides creating, deleting, and arranging the windows themselves - its job is be a server for certain resources used by its clients. As a side benefit, this approach means that the window system can run recursively in one of its windows, or even on another machine.
Plan 9 users do Internet FTP by starting a local program that makes all the files on any FTP server (anywhere on the Internet) appear to be local files. Plan 9 PC users with a DOS/Windows partition on their disk can use the files stored there. ISO 9660 CD-ROMs and tar and cpio tapes all behave as if they were native file systems. The complete I/O behavior and performance of any application can be monitored by running it under a server that sees all its interactions. The debugger can examine a program on another machine even if it is running on a different hardware architecture.
Another example is the approach to networks. In Plan 9, each network
presents itself as a set of files for connection creation,
I/O, and control. A common semantic core for the operations is agreed
upon, together with a general server for translating human-readable
addresses to network-specific ones. As a result, applications don't
care which kind of network (TCP/IP, ISDN, modem)
they are using. In fact, applications
don't even know whether the network they are using is physically
attached to the machine the application is running on: the network
interface files can be imported from another machine.
Hardware and Software:
Subject: What platforms does it run on?
The Plan 9 kernel and applications are highly portable. Plan 9 runs on four major machine architectures: Intel 386/486/Pentium, MIPS, Alpha, and PowerPC. Data structures and protocols are designed for distributed computing on machines of diverse design. Except for necessarily machine-dependent parts of the kernel, the compilers, and a few libraries, there is a single source representation for everything.
To find out whether Plan 9 supports your hardware, read
The Various Ports and
Supported PC Hardware.
Subject: Is anyone working on a port for my system?
Perhaps ... let us know.
Subject: Does it support symmetric multiprocessing?
Yes. The SGI Challenge series of multiprocessors and multi processor Pentiums are supported. Be warned that Intel-based SMP systems are notoriously fickle in conforming to the Multiprocessor Specification and often some head-scratching is required when things don't just work.
The system has been run on machines ranging from dual Pentium 90's
up to quad Xeon 400's and the 8 processor Pentium Pro Axil system.
By default, as it comes out the box,
the release has SMP operation disabled by an option in
the plan9.ini config file.
Subject: What about applications and tools?
Plan 9 comes with its own compilers for C and other languages,
together with all the commands and program-development tools
originally pioneered in the Unix environment.
It also provides newly designed software.
is a programmable debugger that understands multiple-process
programs, and the programs it is debugging may be running
on a hardware platform different from its own.
is a new user interface in which any word on the screen can be interpreted as
by clicking on it, and any string can specify a file to
Subject: Is there a fortran compiler?
No, plan9 does not have a fortran compiler.
If you have fortran programs you want to run, you can try
using the f2c (fortran to C) converter available at
Subject: Where can I get more Plan 9 software?
No, not in the conventional sense. It is written in a strict
dialect of ISO/ANSI C. In a wider sense, its
general design of making all its `objects' look like files to which
one talks in a well-defined protocol shows a related approach.
Subject: What about application portability?
Plan 9 comes with a library that makes it easy to import
There is also a library that emulates the Berkeley socket
Subject: What resources does it need?
As might be expected, the answer depends on what you want to do. The kernel, the window system, and the basic applications will run comfortably on a PC with 8MB of memory.
On the other hand, the system can grow. The installation at
Bell Laboratories includes multiprocessor SGI Challenge and Pentium
machines as CPU servers, and a 350GB Sony WORM disk jukebox
for the file server.
Subject: What GUIs does it support?
The standard interface doesn't use icons or drag-n-drop;
Plan 9 people tend to be text-oriented.
But the window system, the
editor, and the general feel are very mousy, very point-and-click:
Plan 9 windows are much more than a bunch of glass TTYs.
The system supports the graphics primitives and libraries of basic software
for building GUIs.
A screenshot is available at http://plan9.bell-labs.com/plan9dist/screenshot.html
Subject: How do I cut and paste with a 2 button mouse?
Plan 9 really works well only with a three-button mouse.
In the meantime, Shift-Right-button will simulate a middle button,
but that is inadequate for Acme's chording.
Subject: Does Plan 9 have any Unix-like terminal emulators?
The Plan 9 window system doesn't obey any inline cursor controls, since none of the native applications use cursor-addressing. All cursor control in rio, acme and sam is via the mouse.
To see some excellent articles on this important and divisive user interface issue read http://www.asktog.com/readerMail/1999-12ReaderMail.html.
If you want to get from Plan9 to Unix systems,
you can run /bin/vt in one of your windows,
telnet/rlogin to Unix,
and set the term/TERM variable accordingly on the Unix end.
for more details;
note that vt(1) can emulate a VT100 VT220 or ANSI terminal.
Subject: What character set does it use?
The character set is Unicode, the 16-bit set unified with
the ISO 10646 standard for representing languages used throughout the world.
The system and its utilities support Unicode using a byte-stream
representation (called UTF-8) that is compatible with ASCII.
On Plan 9, one may
for Cyrillic strings in a file with
name and see the results appear correctly on the terminal.
Subject: What about security and user authentication?
Plan 9's authentication design is akin to that of MIT's Kerberos.
Passwords are never sent over networks; instead encrypted
tickets are obtained from an authentication server.
It doesn't have the concept of `set UID' programs.
The file server doesn't run user programs, and except at
its own console, it doesn't allow access to protected files
except by authenticated owners. The concept of a special
`root' user is gone.
Subject: How does it communicate with other systems?
The distribution includes a
server that runs on Unix-compatible
systems and understands the native Plan 9 remote file protocol,
so that file systems of Unix machines may be imported into Plan 9.
It also includes an NFS-compatible server that runs on
Plan 9, so that Plan 9 file systems may be accessed
from other systems that support NFS.
It includes the full suite of Internet protocols
(telnet, rlogin, ftp).
Subject: Is it suitable for real time control?
No, it is not. It is a general purpose system,
without an interrupt priority scheme or real scheduler.
Installation and Administration:
Subject: What PC hardware works well with Plan 9?
If you don't want to spend time fiddling with and swapping PC hardware, you may prefer to buy hardware that is in use within Bell Labs, see Supported PC Hardware.
The biggest source of problems is getting the VGA configured on PC terminals. For best performance and functionality, it is recommended that you use a card that can run at 16 bits per pixel or greater, and with hardware-accelerated graphics support; currently only the Mach64 and S3 Virge are supported to this extent. The best buy today seems to be the ATI 8Meg Xpert 98 cards.
For a cpuserver or fileserver any old card that can do CGA is fine.
Subject: How do I Install Plan 9?
The installation is designed to be run from a PC.
If you are having having SCSI problems,
check your cables and terminators.
this is generally the single largest cause of weird SCSI problems.
Active terminators are best.
If you run external cables you need to get high quality ones.
Also, don't crank of the speed on the card.
Subject: How do I setup the VGA?
If the VGA doesn't work, read the last couple sections (Setting Up and Troubleshooting) of "Installing the Plan 9 Distribution"
You will have to find out more about the card so you can configure it. The relevant manuals are: vga(3), vgadb(6), vga(8), and 9load(8).
If your VGA card is not supported, you could try http://mapage.noos.fr/philippe.anel/ for Matrox G200 G400 and G450 drivers by Philippe Anel or see http://plan9.bell-labs.com/wiki/plan9/39/index.html for Riva TNT drivers by Nicholas Waples.
(1st line) in plan9.ini and try again. It may not be of much help but will allow to ask a more specific question.
Subject: How do I control the services that start at boot time?
This is controlled by shell scripts, that are roughly
equivalent to the /etc/rc files on Unix:
/rc/bin/termrc for terminals
/rc/bin/cpurc for cpu servers
for more details.
Subject: How do I setup network services?
For UDP services, you must start them up in the appropriate
For TCP or IL services, you must use the
Subject: How do I shutdown my terminal/cpuserver system?
If you booted from a real fileserver, you can just turn it off.
If you are using kfs, you must halt the
disks manually by typing
at a prompt and waiting for ``kfs: file system halted'' to appear on the screen.
Not doing this means the disk might not
be in a consistent state or modified data
might not have been written out yet;
not halting the disk forces the long wait
at the ``kfs...'' when you boot the next
time while kfs checks the disk.
Subject: How do I reboot my system?
The system can be rebooted by typing ^T^Tr (two control-T's followed by 'r').
Cpu servers can be rebooted by typing ^P on the console.
manual for more details.
Subject: Where did the name come from?
It was chosen in the Bell Labs tradition of selecting names that
make marketeers wince. The developers also wished to pay homage to the
"Plan 9 From Outer Space".
Subject: How can I Obtain Plan 9?
The Plan 9 release is available for free download at
It includes source of the kernel, libraries, and commands for all supported architectures. It also includes complete binaries for the x86 architecture.
Subject: How can I get involved?
The best way to learn about the system
is to write something that other people in the Plan 9
user community could use, or to port the system to new platforms.
Subject: Where can I get more detailed technical information?
The Bell Labs site
stores a wealth of information about the system.
The manual pages are at http://plan9.bell-labs.com/sys/man/
For auxiliary documentation, see http://plan9.bell-labs.com/sys/doc/
A Plan 9 wiki is maintained by enthusiasts at http://plan9.bell-labs.com/wiki/plan9/1/
Subject: Are there any Plan 9 user groups?
There is one in Austin, Texas. See
It's open to anyone, even if you don't live in Austin.
Subject: Is the cross product of two vectors a vector?
No, it is not, and the fact that people treat it as one is the problem.
The *geometric object* that is the closest thing to the c.p. is a skew
tensor (practically the same as wedge product), which (only) in 3D has
Cartesian components that resemble those of a vector, *except* that
this pseudo-vector *flips* under reflection (unlike a genuine vector).
Unfortunately, physicists have been trained to express Maxwell's laws
as a relationship between a genuine vector (field) and a c.p., which
means that that expression of those laws *changes* under reflection,
something that physicists are *not* taught and which appears to have
been overlooked in the analysis of the (nonconservation of) parity
I had to quote Douglas Gwyn verbatim on this, because I have no *ucking clue what he's talking about -- Steve
Subject: Can I emulate Plan 9 under Unix?
Ron Minnich has implemented private name spaces for Linux and FreeBSD. You can get documentation and source code from http://www.acl.lanl.gov/~rminnich/
Several Plan 9 inspired applications are available for Unix systems.
The sam editor is available from ftp://netlib.bell-labs.com/netlib/research/sam.shar.gz
There is also a Windows 95/NT version of Sam, currently distributed in binary form only, available from ftp://netlib.bell-labs.com/netlib/research/sam.exe Comments and bug reports can be sent to firstname.lastname@example.org
Wily is an acme lookalike by Gary Capell. See http://www.cs.yorku.ca/~oz/wily/
Mark H. Wilkinson's 9libs package of Plan 9 emulation libraries for Unix is probably the easiest-to-install distribution of sam and wily. You can get it from http://www.netlib.org/research/9libs/
A free re-implementation of the rc shell is available from http://www.star.le.ac.uk/~tjg/rc/
9wm is David Hogan's lightweight X window manager in the style of 8½/rio. It was once available from ftp://ftp.cs.su.oz.au/dhog/9wm/ but is being moved to a new home. Comments to email@example.com
9term is an 8½ terminal emulator by Matty Farrow, firstname.lastname@example.org, available from ftp://ftp.cs.su.oz.au/matty/unicode/ In the same directory, you'll find a collection of Unicode fonts that can be used with 9term, sam and wily.
9menu is a simple program by Arnold Robbins, email@example.com, that allows you to create X menus from the shell, where each menu item will run a command. 9menu is intended for use with 9wm, but can be used with any other window manager. It is available from ftp://ftp.freefriends.org/arnold/Source/9menu-1.5.shar.gz
Copyright © 1995 Lucent Technologies. All rights reserved.