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Plantilla:Short description

Ignacio.torres/Plan 9
Modifica el valor a Wikidata
Modifica el valor a Wikidata
Tipussistema operatiu distribuït i programari lliure i de codi obert Modifica el valor a Wikidata
Versió inicial
1992 Modifica el valor a Wikidata
Versió estable
Fourth Edition (2002) Modifica el valor a Wikidata
LlicènciaLucent Public License (en) Tradueix
GNU GPL 2.0
llicència MIT Modifica el valor a Wikidata
EpònimBell Labs i Pla 9 des de l'espai Modifica el valor a Wikidata
Característiques tècniques
Plataformax86, x86_64, MIPS, DEC Alpha, PowerPC, SPARC, A32 (en) Tradueix, A64 i ARM Modifica el valor a Wikidata
Escrit enC Modifica el valor a Wikidata
Biblioteca
d'interfície d'usuari		8½ (en) Tradueix i Rio Modifica el valor a Wikidata
Equip
Desenvolupador(s)Bell Labs Modifica el valor a Wikidata
Més informació
Lloc webp9f.org (anglès) Modifica el valor a Wikidata
Guia d'usuariGuia d'usuari Modifica el valor a Wikidata
← Research Unix (en) Tradueix Modifica el valor a Wikidata
Plan 9 from Bell Labs
Installation of Plan 9
Versió inicial1992 (universities) / 1995 (general public)
Versió estableFourth Edition / 2015-01-10[1]
Estat actualUnknown
LlicènciaLucent Public License or GPLv2[2]
Disponible en
English
Característiques tècniques
Plataformax86 / Vx32, x86-64, MIPS, DEC Alpha, SPARC, PowerPC, ARM
Escrit enDialect of ANSI C
Tipus de nucliHybrid kernel
Biblioteca
d'interfície d'usuari		rio / rc
Mètode d'actualitzacióreplica
Equip
Desenvolupador(s)Bell Labs
Més informació
Lloc web9p.io/plan9/

Plan 9 dels Laboratoris Bell(en anglès: Plan 9 from Bell Labs) o simplement Plan 9 és un sistema operatiu distribuït, creat al Centre de recerca en ciencies de la computació (Computing Science Research Center (CSRC)) dels Laboratoris Bell a mitjans dels anys 80, basat en els conceptes UNIX que van ser desenvolupats enlla a finals dels 60. La darrera publicació oficial de codi va ser a principis de 2015.

En Plan 9, la metàfora tot és un fitxer de UNIX s'estén mitjançant un sistema de fitxers en xarxa ubic i l'entrada/sortida per terminal amb cursor adreçable característica dels sistemes tipus UNIX és reemplaçada per un sistema de finestres i interfície gràfica d'usuari sense cursor adreçable tot i que rc, la shell de Plan 9, està basada en text.

El nom Plan 9 from Bell Labs és una referencia a la película de 1959 de sèrie Z Plan 9 from Outer Space.[5] dirigida per Ed Wood. El nom de la mascota del projecte és “Glenda”. El sistema encara es fa servir i el seu desenvolupament continua per part d'investigadors i aficionats.[6][7]

Historia[modifica]

Plan 9 dels Laboratoris Bell el van començar a desenvolupar a finals dels 80[7] membres del mateix grup del Centre de recerca en ciencies de la computació dels Laboratoris Bell que van desenvolupar Unix i el llenguatge de programació C.[8] L'equip de Plan 9 estava originalment liderat per Rob Pike, Ken Thompson, Dave Presotto i Phil Winterbottom, amb el suport de Dennis Ritchie com a director del Departament de Recerca en Tècniques de Computació (Computing Techniques Research Department). Al llarg dels anys molts desenvolupadors destacats han contribuït al projecte, incloent a Brian Kernighan, Tom Duff, Doug McIlroy, Bjarne Stroustrup i Bruce Ellis.[9]

Plan 9 va reemplaçar Unix com a sistema principal per la recerca en sistemes operatius. Va explorar diversos canvis al model Unix original que facilitaven l'ús i la programació del sistema, particularment en entorns distribuïts multiusuari. Passats diversos anys de desenvolupament i ús intern, els Laboratoris Bell van distribuir el sistema operatiu a universitats en 1992. Tres anys després, AT&T va oferir Plan 9 comercialment per mitjà de l'editor de llibres Harcourt Brace. Oferint llicències de codi per 350 dòlars AT&T es dirigia al mercat de sistemes incrustats enlloc del mercat informàtic general. Ritchie va comentar que els desenvolupadors no esperaven generar "molta disrupció" donat el nivell de consolidació d'altres sistemes operatius.[10]

A principis de 1996 AT&T va "deixar de banda" el projecte Plan 9, prioritzant el desenvolupament d' Inferno, destinat a ser un rival per la Plataforma Java de Sun Microsystems.[11] A finals dels anys 90, el nou propietari dels Laboratoris Bell, Lucent Technologies, va deixar d'oferir suport comercial al projecte i el 2000 es va distribuir una tercera versió sota una llicència de codi obert, seguida el 2002 per una quarta versió sota una nova llicència de programari lliure.[12]

Una comunitat d’usuaris i desenvolupadors, inclòs el personal actual i anterior dels Laboratoris Bell, va produir edicions diaries en forma de imatge ISO mentre els Laboratoris Bell hostatjaven el projecte de desenvolupament.[13] Es pot accedir al repositori de codi mitjançant els protocols 9P i HTTP i es fa servir per actualitzar instal·lacions existents. [14] A més dels components oficials del sistema operatiu inclosos en les imatges ISO, els Laboratoris Bell també hostatgen un repositori d'aplicacions i eines de tercers.[15]

El desenvolupament del sistema Plan 9 s'ha aturat en els darrers anys a mida que els Laboratoris Bell han passat a treballar en projectes posteriors. El desenvolupament no oficial del sistema continua al fork 9front, on els col·laboradors actius proporcionen muntatges mensuals i noves funcionalitats. Fins ara, el fork 9front ha proporcionat controladors Wi-Fi, controladors d'àudio, suport USB i un emulador de jocs juntament amb altres funcions.[16] Hi ha altres sistemes operatius recents basats en Plan 9 com Harvey OS[17] i Jehanne OS.[18]

Data Lliurament Comentari
1992 Plan 9 Primera Edició Lliurat a universitats pels Laboratoris Bell
1995 Plan 9 Segona Edició Lliurat pels Laboratoris Bell pel seu ús no comercial[19]
2000 Plan 9 Tercera Edició. (Brazil) Lliurat per Lucent Technologies sota una llicència de codi obert
2002 Plan 9 Cuarta Edició Lliurat per Lucent Technologies sota una llicència de programari lliure

Design concepts[modifica]

Plan 9 from Bell Labs is like the Quakers: distinguished by its stress on the 'Inner Light,' noted for simplicity of life, in particular for plainness of speech. Like the Quakers, Plan 9 does not proselytize.

——Sape J. Mullender, Pierre G. Jansen.
Real Time in a Real Operating System[20]

Plan 9 is a distributed operating system, designed to make a network of heterogeneous and geographically separated computers function as a single system.[21] In a typical Plan 9 installation, users work at terminals running the window system rio, and they access CPU servers which handle computation-intensive processes. Permanent data storage is provided by additional network hosts acting as file servers and archival storage.[22]

Its designers state that,


Wikiquote A Viquidites hi ha citacions, dites populars i frases fetes relatives a [[Q:[t]he foundations of the system are built on two ideas: a per-process name space and a simple message-oriented file system protocol.|Pike et al.[23]]]

The first idea means that, unlike on most operating systems, processes (running programs) each have their own view of the namespace, corresponding to what other operating systems call the file system; a single path name may refer to different resources for different processes. The potential complexity of this setup is controlled by a set of conventional locations for common resources.[24][25]

The second idea means that processes can offer their services to other processes by providing virtual files that appear in the other processes' namespace. The client process's input/output on such a file becomes inter-process communication between the two processes. This way, Plan 9 generalizes the Unix notion of the filesystem as the central point of access to computing resources. It carries over Unix's idea of device files to provide access to peripheral devices (mice, removable media, etc.) and the possibility to mount filesystems residing on physically distinct filesystems into a hierarchical namespace, but adds the possibility to mount a connection to a server program that speaks a standardized protocol and treat its services as part of the namespace.

For example, the original window system, called 8½, exploited these possibilities as follows. Plan 9 represents the user interface on a terminal by means of three pseudo-files: mouse, which can be read by a program to get notification of mouse movements and button clicks, cons, which can be used to perform textual input/output, and bitblt, writing to which enacts graphics operations (see bit blit). The window system multiplexes these devices: when creating a new window to run some program in, it first sets up a new namespace in which mouse, cons and bitblt are connected to itself, hiding the actual device files to which it itself has access. The window system thus receives all input and output commands from the program and handles these appropriately, by sending output to the actual screen device and giving the currently focused program the keyboard and mouse input.[22] The program does not need to know if it is communicating directly with the operating system's device drivers, or with the window system; it only has to assume that its namespace is set up so that these special files provide the kind of input and accept the kind of messages that it expects.

Plan 9's distributed operation relies on the per-process namespaces as well, allowing client and server processes to communicate across machines in the way just outlined. For example, the cpu command starts a remote session on a computation server. The command exports part of its local namespace, including the user's terminal's devices (mouse, cons, bitblt), to the server, so that remote programs can perform input/output using the terminal's mouse, keyboard and display, combining the effects of remote login and a shared network filesystem.[22][23]

9P protocol[modifica]

Article principal: 9P (protocol)

All programs that wish to provide services-as-files to other programs speak a unified protocol, called 9P. Compared to other systems, this reduces the number of custom programming interfaces. 9P is a generic, medium-agnostic, byte-oriented protocol that provides for messages delivered between a server and a client.[26] The protocol is used to refer to and communicate with processes, programs, and data, including both the user interface and the network.[27] With the release of the 4th edition, it was modified and renamed 9P2000.[12]

Unlike most other operating systems, Plan 9 does not provide special application programming interfaces (such as Berkeley sockets, X resources or ioctl system calls) to access devices.[26] Instead, Plan 9 device drivers implement their control interface as a file system, so that the hardware can be accessed by the ordinary file input/output operations read and write. Consequently, sharing the device across the network can be accomplished by mounting the corresponding directory tree to the target machine.[5]

Union directories and namespaces[modifica]

Plan 9 allows the user to collect the files (called names) from different directory trees in a single location. The resulting union directory behaves as the concatenation of the underlying directories (the order of concatenation can be controlled); if the constituent directories contain files having the same name, a listing of the union directory (ls or lc) will simply report duplicate names.[28] Resolution of a single path name is performed top-down: if the directories top and bottom are unioned into u with top first, then u/name denotes top/name if it exists, bottom/name only if it exists and top/name does not exist, and no file if neither exists. No recursive unioning of subdirectories is performed, so if top/subdir exists, the files in bottom/subdir are not accessible through the union.[29]

A union directory can be created by using the bind command: 

; bind /arm/bin /bin
; bind -a /acme/bin/arm /bin
; bind -b /usr/alice/bin /bin

In the example above, /arm/bin is mounted at /bin, the contents of /arm/bin replacing the previous contents of /bin. Acme's bin directory is then union mounted after /bin, and Alice's personal bin directory is union mounted before. When a file is requested from /bin, it is first looked for in /usr/alice/bin, then in /arm/bin, and then finally in /acme/bin/arm.

The separate process namespaces thus replace the notion of a search path in the shell. Where Unix shells have a list of directories to search for programs when given a command, the Plan 9 shell only looks in the directory /bin; adding commands is done by binding several directories together to appear as a single /bin.[22]

Furthermore, the kernel can keep separate mount tables for each process,[20] and can thus provide each process with its own file system namespace. Processes' namespaces can be constructed independently, and the user may work simultaneously with programs that have heterogeneous namespaces.[23] Namespaces may be used to create an isolated environment similar to chroot, but in a more secure way.[26]

Plan 9's union directory architecture inspired 4.4BSD and Linux union file system implementations,[28] although the developers of the BSD union mounting facility found the non-recursive merging of directories in Plan 9 "too restrictive for general purpose use".[29]

Special virtual filesystems[modifica]

/proc[modifica]

Listing processes with list contents of directory (ls, lc) command[30] in /proc
Article principal: procfs

Instead of having system calls specifically for process management, Plan 9 provides the /proc file system. Each process appears as a directory containing information and control files which can be manipulated by the ordinary file IO system calls.[31]

The file system approach allows Plan 9 processes to be managed with simple file management tools such as ls and cat; however, the processes cannot be copied and moved as files.[3]

/net[modifica]

Plan 9 does not have specialised system calls or ioctls for accessing the networking stack or networking hardware. Instead, the /net file system is used. Network connections are controlled by reading and writing control messages to control files. Sub-directories such as /net/tcp and /net/udp are used as an interface to their respective protocols.[3]

Unicode[modifica]

Vegeu també: UTF-8 i Comparison of Unicode encodings

To reduce the complexity of managing character encodings, Plan 9 uses Unicode throughout the system. The initial Unicode implementation was ISO 10646. Ken Thompson invented UTF-8, which became the native encoding in Plan 9. The entire system was converted to general use in 1992.[32] UTF-8 preserves backwards compatibility with traditional null-terminated strings, enabling more reliable information processing and the chaining of multilingual string data with Unix pipes between multiple processes. Using a single UTF-8 encoding with characters for all cultures and regions eliminates the need for switching between code sets.[33]

Combining the design concepts[modifica]

Though interesting on their own, the design concepts of Plan 9 were supposed to be most useful when combined together. For example, to implement a network address translation (NAT) server, a union directory can be created, overlaying the router's /net directory tree with its own /net. Similarly, a virtual private network (VPN) can be implemented by overlaying in a union directory a /net hierarchy from a remote gateway, using secured 9P over the public Internet. A union directory with the /net hierarchy and filters can be used to sandbox an untrusted application or to implement a firewall.[26] In the same manner, a distributed computing network can be composed with a union directory of /proc hierarchies from remote hosts, which allows interacting with them as if they are local.

When used together, these features allow for assembling a complex distributed computing environment by reusing the existing hierarchical name system.[3]

Software for Plan 9[modifica]

Vegeu també: List of Plan 9 applications

As a benefit from the system's design, most tasks in Plan 9 can be accomplished by using ls, cat, grep, cp and rm utilities in combination with the rc shell (the default Plan 9 shell).

Factotum is an authentication and key management server for Plan 9. It handles authentication on behalf of other programs such that both secret keys and implementation details need only be known to Factotum.[34]

Graphical programs[modifica]

Plan 9 running acme and rc

Unlike Unix, Plan 9 was designed with graphics in mind.[27] After booting, a Plan 9 terminal will run the rio windowing system, in which the user can create new windows displaying rc.[35] Graphical programs invoked from this shell replace it in its window.

The plumber provides an inter-process communication mechanism which allows system-wide hyperlinking.

Sam and acme are Plan 9's text editors.[36]

Storage system[modifica]

Plan 9 supports the Kfs, Paq, Cwfs, FAT, and Fossil file systems. The last was designed at Bell Labs specifically for Plan 9 and provides snapshot storage capability. It can be used directly with a hard drive or backed with Venti, an archival file system and permanent data storage system.

Software development[modifica]

The distribution package for Plan 9 includes special compiler variants and programming languages, and provides a tailored set of libraries along with a windowing user interface system specific to Plan 9.[37] The bulk of the system is written in a dialect of C (ANSI C with some extensions and some other features left out). The compilers for this language were custom built with portability in mind; according to their author, they "compile quickly, load slowly, and produce medium quality object code".[38]

A concurrent programming language called Alef was available in the first two editions, but was then dropped for maintenance reasons and replaced by a threading library for C.[39][40]

Unix compatibility[modifica]

Though Plan 9 was supposed to be a further development of Unix concepts, compatibility with preexisting Unix software was never the goal for the project. Many command-line utilities of Plan 9 share the names of Unix counterparts, but work differently.[30]

Plan 9 can support POSIX applications and can emulate the Berkeley socket interface through the ANSI/POSIX Environment (APE) that implements an interface close to ANSI C and POSIX, with some common extensions (the native Plan 9 C interfaces conform to neither standard). It also includes a POSIX-compatible shell. APE's authors claim to have used it to port the X Window System (X11) to Plan 9, although they do not ship X11 "because supporting it properly is too big a job".[41] Some Linux binaries can be used with the help of a "linuxemu" (Linux emulator) application; however, it is still a work in progress.[42] Vice versa, the vx32 virtual machine allows a slightly modified Plan 9 kernel to run as a user process in Linux, supporting unmodified Plan 9 programs.[43]

Reception[modifica]

Comparison to contemporary operating systems[modifica]

In 1991, Plan 9's designers compared their system to other early nineties operating systems in terms of size, showing that the source code for a minimal ("working, albeit not very useful") version was less than one-fifth the size of a Mach microkernel without any device drivers (5899 or 4622 lines of code for Plan 9, depending on metric, vs. 25530 lines). The complete kernel comprised 18000 lines of code.[22] (According to a 2006 count, the kernel was then some 150,000 lines, but this was compared against more than 4.8 million in Linux.[26])

Within the operating systems research community, as well as the commercial Unix world, other attempts at achieving distributed computing and remote filesystem access were made concurrently with the Plan 9 design effort. These included the Network File System and the associated vnode architecture developed at Sun Microsystems, and more radical departures from the Unix model such as the Sprite OS from UC Berkeley. Sprite developer Brent Welch points out that the SunOS vnode architecture is limited compared to Plan 9's capabilities in that it does not support remote device access and remote inter-process communication cleanly, even though it could have, had the preexisting UNIX domain sockets (which "can essentially be used to name user-level servers") been integrated with the vnode architecture.[24]

One critique of the "everything is a file", communication-by-textual-message design of Plan 9 pointed out limitations of this paradigm compared to the typed interfaces of Sun's object-oriented operating system, Spring:


Wikiquote A Viquidites hi ha citacions, dites populars i frases fetes relatives a [[Q:Plan 9 constrains everything to look like a file. In most cases the real interface type comprises the protocol of messages that must be written to, and read from, a file descriptor. This is difficult to specify and document, and prohibits any automatic type checking at all, except for file errors at run time. (...)

[A] path name relative to a process' implicit root context is the only way to name a service. Binding a name to an object can only be done by giving an existing name for the object, in the same context as the new name. As such, interface references simply cannot be passed between processes, much less across networks. Instead, communication has to rely on conventions, which are prone to error and do not scale.|Roscoe; emphasis in the original.[44]]]

A later retrospective comparison of Plan 9, Sprite and a third contemporary distributed research operating system, Amoeba, found that


Wikiquote A Viquidites hi ha citacions, dites populars i frases fetes relatives a [[Q:the environments they [Amoeba and Sprite] build are tightly coupled within the OS, making communication with external services difficult. Such systems suffer from the radical departure from the UNIX model, which also discourages portability of already existing software to the platform (...). The lack of developers, the very small range of supported hardware and the small, even compared to Plan 9, user base have also significantly slowed the adoption of those systems (...). In retrospect, Plan 9 was the only research distributed OS from that time which managed to attract developers and be used in commercial projects long enough to warrant its survival to this day.|Mirtchovski, Simmonds and Minnich[45]]]

Impact[modifica]

The wmii X window manager was inspired by acme, a text editor from the Plan 9 project.[46]

Plan 9 demonstrated that an integral concept of Unix—that every system interface could be represented as a set of files—could be successfully implemented in a modern distributed system.[35] Some features from Plan 9, like the UTF-8 character encoding of Unicode, have been implemented in other operating systems. Unix-like operating systems such as Linux have implemented 9P, Plan 9's file system, and have adopted features of rfork, Plan 9's process creation mechanism.[47] Additionally, in Plan 9 from User Space, several of Plan 9's applications and tools, including the sam and acme editors, have been ported to Unix and Linux systems and have achieved some level of popularity. Several projects seek to replace the GNU operating system programs surrounding the Linux kernel with the Plan 9 operating system programs.[48][49] The 9wm window manager was inspired by 8½, the older windowing system of Plan 9;[50] wmii is also heavily influenced by Plan 9.[46] In computer science research, Plan 9 has been used as a grid computing platform[51][45] and as a vehicle for research into ubiquitous computing without middleware.[52] In commerce, Plan 9 underlies Coraid storage systems. However, Plan 9 has never approached Unix in popularity, and has been primarily a research tool:

Wikiquote A Viquidites hi ha citacions, dites populars i frases fetes relatives a [[Q:[I]t looks like Plan 9 failed simply because it fell short of being a compelling enough improvement on Unix to displace its ancestor. Compared to Plan 9, Unix creaks and clanks and has obvious rust spots, but it gets the job done well enough to hold its position. There is a lesson here for ambitious system architects: the most dangerous enemy of a better solution is an existing codebase that is just good enough.|Eric S. Raymond[5]]]

Other factors that contributed to low adoption of Plan 9 include the lack of commercial backup, the low number of end-user applications, and the lack of device drivers.[35][36]

Plan 9 proponents and developers claim that the problems hindering its adoption have been solved, that its original goals as a distributed system, development environment, and research platform have been met, and that it enjoys moderate but growing popularity.[cal citació] Inferno, through its hosted capabilities, has been a vehicle for bringing Plan 9 technologies to other systems as a hosted part of heterogeneous computing grids.[53][54][55]

Several projects work to extend Plan 9, including 9atom and 9front. These forks augment Plan 9 with additional hardware drivers and software, including an improved version of the Upas e-mail system, the go compiler, Mercurial version control system support, and other programs.[7][56] Plan 9 was ported to the Raspberry Pi single-board computer.[57][58] The Harvey project attempts to replace the custom Plan 9 C compiler with GCC, to leverage modern development tools such as GitHub and Coverity, and speed up development.[59]

Derivatives and forks[modifica]

Inferno is a descendant of Plan 9, and shares many design concepts and even source code in the kernel, particularly around devices and the Styx/9P2000 protocol. Inferno shares with Plan 9 the Unix heritage from Bell Labs and the Unix philosophy. Many of the command line tools in Inferno were Plan 9 tools that were translated to Limbo.

  • 9atom[60] augments the Plan 9 distribution with the addition of a 386 PAE kernel, an amd64 cpu and terminal kernel, nupas, extra pc hardware support, IL and Ken's fs.
  • 9front[61] is a fork of Plan 9. It was started to remedy a perceived lack of devoted development resources inside Bell Labs, and has accumulated various fixes and improvements.
  • 9legacy[62] is an alternative distribution. It includes a set of patches based on the current Plan 9 distribution.
  • Akaros[63] is designed for many-core architectures and large-scale SMP systems.
  • Harvey OS[64] is an effort to get the Plan 9 code working with gcc and clang.
  • JehanneOS[65] is an experimental OS derived from Plan 9. Its userland and modules are mostly derived from 9front, its build system from Harvey OS, and its kernel is a fork of the Plan9-9k 64-bit Plan9 kernel.
  • NIX[66] is a fork of Plan9 aimed at multicore systems and cloud computing.

License[modifica]

Starting with the release of Fourth edition on April 2002,[12] the full source code of Plan 9 from Bell Labs is freely available under Lucent Public License 1.02, which is considered to be an open-source license by the Open Source Initiative (OSI), free software license by the Free Software Foundation, and it passes the Debian Free Software Guidelines.[26]

In February 2014, the University of California, Berkeley, was authorized by the current Plan 9 copyright holder – Alcatel-Lucent – to release all Plan 9 software previously governed by the Lucent Public License, Version 1.02 under the GNU General Public License, Version 2.[67]

See also[modifica]

References[modifica]

  1. ↑ «plan9checksums». Bell Labs. Arxivat de l'original el 2017-06-01. [Consulta: 25 juliol 2019]. «Sat Jan 10 04:04:55 EST 2015 ... plan9.iso.bz2»
  2. ↑ http://akaros.cs.berkeley.edu/files/Plan9License
  3. ↑ 3,0 3,1 3,2 3,3 Pike, R.; Presotto, D.; Dorward, S.; Flandrena, B.; Thompson, K. «Plan 9 from Bell Labs». Bell Labs. Lucent Technologies. [Consulta: 26 febrer 2016].
  4. ↑ Lucent Technologies. «Glenda, the Plan 9 Bunny», 2006. [Consulta: 2 desembre 2008].
  5. ↑ 5,0 5,1 5,2 Raymond, Eric S. «Plan 9: The Way the Future Was». A: The Art of UNIX Programming. Addison-Wesley, 2003-09-17. ISBN 0-13-142901-9 [Consulta: 7 maig 2007]. 
  6. ↑ Robertson, James. «Plan 9 Forked, Continues as 9front». OSNews, 16-07-2011. [Consulta: 31 desembre 2011].
  7. ↑ 7,0 7,1 7,2 «9atom». [Consulta: 11 novembre 2011].
  8. ↑ Lucent Technologies (1995-07-18). "From the inventors of UNIX system comes Plan 9 from Bell Labs". Nota de premsa.
  9. ↑ McIlroy, Doug. «Preface». Bell Labs. Lucent Technologies, Mar 1995. [Consulta: 26 febrer 2016].
  10. ↑ Lee, Yvonne L. «AT&T Bell Labs ships Plan 9 OS for embedded systems». , 24-07-1995.
  11. ↑ Pontin, Jason «AT&T reveals plans for Java competitor». , 19-02-1996, p. 3.
  12. ↑ 12,0 12,1 12,2 Loli-Queru, Eugenia. «Bell Labs Releases New Version of Plan 9». OSNews, 29-04-2002. [Consulta: 31 desembre 2011].
  13. ↑ «How to contribute». Bell Labs. Lucent Technologies. [Consulta: 30 novembre 2011].
  14. ↑ «Staying up to date». Bell Labs. Lucent Technologies. [Consulta: 24 juliol 2019].
  15. ↑ «Plan 9 — Additional Software», 2009. [Consulta: 6 març 2016].
  16. ↑ «FQA 1 - Introduction To 9front». fqa.9front.org. [Consulta: 15 febrer 2018].
  17. ↑ «Harvey OS» (en anglès). harvey-os.org. [Consulta: 15 febrer 2018].
  18. ↑ «Jehanne». jehanne.io. [Consulta: 15 febrer 2018].
  19. ↑ «Announcement of the first release to general public». 9 fans, 16-07-1995. Arxivat de l'original el 2008-07-06.
  20. ↑ 20,0 20,1 Mullender, Sape J.; Jansen, Pierre G. «Real Time in a Real Operating System». A: Herbert, Andrew J.. Computer systems: theory, technology, and applications: a tribute to Roger Needham. Springer Science+Business Media, 2004-02-26, p. 211. ISBN 978-0-387-20170-2 [Consulta: 24 desembre 2011]. 
  21. ↑ Hancock, Brian «Reinventing Unix: an introduction to the Plan 9 operating system». Library Hi Tech. MCB UP, vol. 21, 4, 2003, pàg. 471–76. DOI: 10.1108/07378830310509772.
  22. ↑ 22,0 22,1 22,2 22,3 22,4 "Plan 9, A Distributed System" a Proc. Spring 1991 EurOpen Conference.  
  23. ↑ 23,0 23,1 23,2 Pike, R.; Presotto, D.; Thompson, K.; Trickey, H.; Winterbottom, P. «The Use of Name Spaces in Plan 9». Bell Labs. [Consulta: 26 febrer 2016].
  24. ↑ 24,0 24,1 Welch, Brent «A comparison of three distributed file system architectures: Vnode, Sprite, and Plan 9». Computing Systems, vol. 7, 2, 1994, pàg. 175–199.
  25. ↑ namespace(4)
  26. ↑ 26,0 26,1 26,2 26,3 26,4 26,5 Pereira, Uriel M. (2006). The Unix Spirit set Free: Plan 9 from Bell Labs (AVI). FOSDEM. Consulta: 2011-12-02. 
  27. ↑ 27,0 27,1 Minnich, Ron. «Why Plan 9 is not dead yet And What we can learn from it» (PDF). Los Alamos National Laboratory, 2005. Arxivat de l'original el 2016-02-25. [Consulta: 26 febrer 2016].
  28. ↑ 28,0 28,1 Valerie, Aurora. «Union file systems: Implementations, part I». LWN.net, 25-03-2009. [Consulta: 5 desembre 2011].
  29. ↑ 29,0 29,1 (1995) "Union Mounts in 4.4BSD-Lite" a Proc. Winter USENIX Conf..  
  30. ↑ 30,0 30,1 «UNIX to Plan 9 command translation». Bell Labs. Lucent Technologies. [Consulta: 2 desembre 2011].
  31. ↑ Ballesteros, Francisco J. «Introduction to OS abstractions using Plan 9 from Bell Labs» (pdf). Universidad Rey Juan Carlos, 28-09-2007. Arxivat de l'original el 2010-09-22.
  32. ↑ Pike, Rob. «UTF-8 History», 30-04-2003. [Consulta: 27 abril 2006].
  33. ↑ Lunde, Ken. CJKV information processing. O'Reilly Media, Jan 1999, p. 466. ISBN 978-1-56592-224-2 [Consulta: 23 desembre 2011]. 
  34. ↑ Cox, R.; Grosse, E.; Pike, R.; Presotto, D.; Quinlan, S. «Security in Plan 9». Bell Labs. Lucent Technologies. [Consulta: 26 febrer 2016].
  35. ↑ 35,0 35,1 35,2 Hudson, Andrew. «Investigating the Plan 9 Operating System». OSNews, 19-07-2006. [Consulta: 31 desembre 2011].
  36. ↑ 36,0 36,1 «An interview with Russ Cox». The Setup. Uses this, 09-04-2011. [Consulta: 1r gener 2012].
  37. ↑ Dixon, Rod. Open source software law. Artech House, 2004, p. 213. ISBN 978-1-58053-719-3 [Consulta: 25 desembre 2011]. 
  38. ↑ Thompson, Ken «A new C Compiler». Australian UNIX systems User Group Newsletter. AUUG [[[Kensington, New South Wales|Kensington]], AU], vol. 13, 1, February 1992, pàg. 31–41. ISSN: 1035-7521 [Consulta: 25 desembre 2011].
  39. ↑ Pike, Rob. «Rio: Design of a Concurrent Window System». [Consulta: 8 març 2013].
  40. ↑ thread(2)
  41. ↑ Trickey, Howard. «APE – The ANSI/POSIX Environment». Bell Labs. Lucent Technologies. [Consulta: 26 febrer 2016].
  42. ↑ «Linux emulation». Bell Labs. Lucent Technologies. [Consulta: 26 febrer 2016].
  43. ↑ (2008) "Vx32: Lightweight, User-level Sandboxing on the x86" a USENIX Annual Tech. Conf.. : 293–306 
  44. ↑ (tesi). 
  45. ↑ 45,0 45,1 (2004) "Plan 9—an integrated approach to grid computing" a Proc. 18th Int'l Parallel and Distributed Processing Symp.. , IEEE 
  46. ↑ 46,0 46,1 «window manager improved 2». suckless.org. Arxivat de l'original el 2011-12-31. [Consulta: 2 gener 2012]. «[wmii] has a 9p filesystem interface and supports classic and tiling (acme-like) window management.»
  47. ↑ Torvalds, Linus. «The Linux edge». A: Open Sources: Voices from the Open Source Revolution. O'Reilly, 1999. ISBN 1-56592-582-3. 
  48. ↑ «Glendix: Bringing the beauty of Plan 9 to Linux». [Consulta: 1r desembre 2011].
  49. ↑ «Plan 9 From Gentoo: Plan 9 Meets Gentoo». Gentoo Linux. Arxivat de l'original el 2012-12-20. [Consulta: 1r desembre 2011].
  50. ↑ «The 9wm Window Manager». 9wm. [Consulta: 2 gener 2012]. «9wm is an X window manager which attempts to emulate the Plan 9 window manager 8-1/2 as far as possible within the constraints imposed by X.»
  51. ↑ «9grid». Bell Labs. Lucent Technologies. Arxivat de l'original el 2006-03-14. [Consulta: 28 març 2006].
  52. ↑ (2005) "Traditional systems can work well for pervasive applications. A case study: Plan 9 from Bell Labs becomes ubiquitous" a IEEE Intl' Conf. on Pervasive Computing and Communications.  
  53. ↑ Vita Nuova (2004-05-18). "Vita Nuova Supplies Inferno Grid to Evotec OAI" (PDF). Nota de premsa. Consulta: 2006-03-28.
  54. ↑ Vita Nuova (2004-05-12). "Rutgers University Libraries Install Inferno Data Grid" (PDF). Nota de premsa. Consulta: 2006-03-28.
  55. ↑ Vita Nuova (2004-05-04). "The University of York Department of Biology install Vita Nuova's Inferno Data Grid" (PDF). Nota de premsa. Consulta: 2006-03-28.
  56. ↑ «plan9front – the front fell off». [Consulta: 1r desembre 2011].
  57. ↑ Hayward, David. «Raspberry Pi operating systems: 5 reviewed and rated». TechRadar, 09-05-2013. Arxivat de l'original el June 7, 2013. [Consulta: 20 abril 2014].
  58. ↑ «How to install Plan 9 on a Raspberry Pi». eLinux. [Consulta: 16 novembre 2014].
  59. ↑ "Harvey" a USENIX ATC BOF session.  
  60. ↑ «9atom».
  61. ↑ «9FRONT.ORG THE PLAN FELL OFF».
  62. ↑ «9legacy».
  63. ↑ http://akaros.cs.berkeley.edu
  64. ↑ «Harvey OS».
  65. ↑ «JehanneOS».
  66. ↑ «NIX».
  67. ↑ Sharwood, Simon. «Plan 9 moves out from Lucent licence space». TheRegister, 14-02-2014. [Consulta: 20 abril 2014].

External links[modifica]

A Wikimedia Commons hi ha contingut multimèdia relatiu a: Ignacio.torres/Plan 9
  • 9p.io: Archived mirror of the original official Plan 9 Web site at plan9.bell-labs.com
  • 9fans: Semi-official mailing list for Plan 9 users and developers

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