Encyclopedia
Unix or
UNIX is a
computer operating system originally developed in the 1960s and 1970s by a group of
AT&T Bell Labs employees including
Ken Thompson,
Dennis Ritchie, and Douglas McIlroy. Today's Unix systems are split into various branches, developed over time by AT&T, several other commercial vendors, as well as several non-profit organizations.
The present owner of the UNIX
trademark is The Open Group, while the present claimants on the rights to the UNIX
source code are
SCO Group and
Novell . Only systems fully compliant with and certified to the Single UNIX Specification qualify as "UNIX" .
During the late 1970s and early 1980s, Unix's influence in academic circles led to large-scale adoption of Unix by commercial startups, the most notable of which is
Sun Microsystems. Today, in addition to certified UNIX systems, Unix-like operating systems such as
Linux and
Mac OS X are commonly encountered.
Sometimes,
Traditional Unix may be used to describe a Unix or an operating system that has the characteristics of either Version 7 Unix or
UNIX System V.
Overview
Unix operating systems are widely used in both servers and
workstations. The Unix environment and the client-server program model were essential elements in the development of the
Internet and the reshaping of computing as centered in
networks rather than in individual computers.
Both Unix and C were developed by AT&T and distributed to government and academic institutions, causing it to be ported to a wider variety of machine families than any other operating system. As a result, Unix became synonymous with "open systems."
Unix was designed to be portable, multi-tasking and multi-user in a time-sharing configuration. The Unix systems are characterized by various concepts: plain text files, command line interpreter, hierarchical file system, treating devices and certain types of inter-process communication as files, etc. In software engineering, Unix is mainly noted for its use of the
C programming language and for the Unix philosophy.
The system is also known for the use of a large number of small programs that can be strung together to complete a task with a pipe, as opposed to using a single larger program that includes all of the same functionality. The result is more flexibility and improved development; since each program is small and dedicated to a single role, it is much easier to understand and debug.
Under Unix, the "operating system" consists of many of these utilities along with the master control program, the kernel. The kernel provides services to start and stop programs, handle the file system and other common "high level" tasks that most programs share, and, perhaps most importantly, schedules access to hardware to avoid conflicts if two programs attempt to simultaneously access the same resource or device. In order to mediate such access, the kernel was given special rights on the system and led to the division between
user-space and
kernel-space.
The
microkernel tried to reverse the growing size of kernels and return to a system in which most tasks would be completed by smaller utilities. In an era when a "normal" computer consisted of a hard disk for storage and a printer for input/output, the Unix file model worked quite well as most I/O was "linear". However, modern systems include networking and other new devices. Describing a graphical user interface driven by mouse control in an "event driven" fashion didn't work well under the old model. Work on systems supporting these new devices in the 1980s led to facilities for non-blocking I/O and other forms of inter-process communications than just pipes, as well as methods for moving functionality such as network protocols out of the kernel.
History
1960s and 1970s
In the 1960s, the
Massachusetts Institute of Technology, AT&T Bell Labs, and
General Electric worked on an experimental operating system called Multics , which was designed to run on the GE-645
mainframe computer. The aim was the creation of a commercial product, although this was never a great success. Multics was an interactive operating system with many novel capabilities, including enhanced
security. The project did develop production releases, but initially these releases performed poorly.
AT&T Bell Labs pulled out and deployed its resources elsewhere. One of the developers on the Bell Labs team, Ken Thompson, continued to develop for the GE-645 mainframe, and wrote a game for that computer called Space Travel. However, he found that the game was too slow on the GE machine and was costly, costing $75 per execution in scarce computing time.
Thompson thus re-wrote the game in
DEC PDP-7 Assembly language with help from Dennis Ritchie. This experience, combined with his work on the Multics project, led Thompson to start a new operating system for the DEC PDP-7. Thompson and Ritchie led a team of developers, including Rudd Canaday, at Bell Labs developing a file system as well as the new multi-tasking operating system itself. They included a command line interpreter and some small utility programs. This project was called
Unics, short for
Uniplexed
Information and
Computing
System, and could support two simultaneous users. The name has been attributed to Brian Kernighan, and was a hack on
Multics. Unics is also a homophone of
eunuchs, making the system a "castrated Multics". The name was later changed to Unix. The name is also a criticism of the overly general and bloated Multics system - Unix would do one thing, and do it well.
Up until this point there had been no financial support from Bell Labs. When the Computer Science Research Group wanted to use Unix on a much larger machine than the PDP-7, Thompson and Ritchie managed to trade the promise of adding text processing capabilities to Unix for a
PDP-11/20 machine. This led to some financial support from Bell. For the first time in 1970, the Unix Operating System was officially named and ran on the PDP-11/20. It added a text formatting program called roff and a
text editor. All three were written in PDP-11/20 assembly language. Bell Labs used this initial "text processing system", made up of Unix, roff, and the editor, for text processing of
patent applications. Roff soon evolved into troff, the first electronic publishing program with a full
typesetting capability. The
UNIX Programmer's Manual was published on November 3, 1971.
In 1973, the decision was made to re-write Unix in the C programming language. The change meant that it was easier to modify Unix to work on other machines , and other developers could create variations. The code was now more concise and compact, leading to accelerated development of Unix. AT&T made Unix available to universities and commercial firms, as well as the
United States government under licenses. The licenses included all source code except for the machine-dependent kernel, which was written in PDP-11 assembly code. However, bootleg copies of the annotated Unix machine-dependent kernel circulated widely in the late 1970s in the form of a much-copied book by John Lions of the
University of New South Wales in
Australia , which led to considerable adoption of Unix as an educational operating system.
Versions of the Unix system were determined by editions of its user manuals, so that "Fifth Edition Unix" and "Unix Version 5" have both been used to designate the same thing.
Development expanded, with Versions 4, 5, and 6 being released by 1975. These versions added
pipes, leading to the development of a more modular code-base, increasing development speed still further. Version 5 and especially Version 6 led to a plethora of different Unix versions both inside and outside Bell Labs, including PWB/UNIX, IS/1 , and the
University of Wollongong's port to the Interdata 7/32 .
In 1978, UNIX/32V, for the
VAX, was released. By this time, over 600 machines were running Unix in some form. Version 7 Unix, the last version of Research Unix to be released widely, was released in 1979. Versions 8, 9 and 10 were developed through the 1980s but were only ever released to a few universities, though they did generate papers describing the new work. This research led to the development of
Plan 9, a new portable distributed system.
1980s
AT&T now licensed UNIX System III, based largely on Version 7, for commercial use, the first version launching in 1982. This also included support for the
DEC VAX machine. AT&T also continued to issue licenses for older Unix versions. To end the confusion between all its differing internal versions, AT&T combined them into
UNIX System V Release 1. This introduced a few features such as the
vi editor and curses from the
Berkeley Software Distribution of Unix developed at the
University of California, Berkeley. This also included support for the
DEC VAX machine, as well as the
Western Electric 3B series of machines.
Since the newer commercial UNIX licensing terms were not as favorable for academic use as the older versions of Unix, the Berkeley researchers continued to develop BSD Unix as an alternative to UNIX System III and V, originally on the PDP-11 architecture and later for the VAX-11 . Many contributions to Unix first appeared on BSD systems, notably the C shell with job control , Perhaps the most important aspect of the BSD development effort was the addition of
TCP/IP network code to the mainstream Unix kernel. The BSD effort produced several significant releases that contained network code: 4.1cBSD, 4.2BSD, 4.3BSD, 4.3BSD-Tahoe , Net/1, 4.3BSD-Reno , Net/2, 4.4BSD, and 4.4BSD-lite. The network code found in these releases is the ancestor of almost all TCP/IP network code in use today, including code that was later released in AT&T System V UNIX and
Microsoft Windows. The accompanying Berkeley Sockets API is a de facto standard for networking APIs and has been copied on many platforms.
Other companies began to offer commercial versions of the UNIX System for their own mini-computers and workstations. Most of these new Unix flavors were developed from the System V base under a license from AT&T; however, others were based on BSD instead. One of the leading developers of BSD,
Bill Joy, went on to co-found
Sun Microsystems in 1982 and create SunOS for their
workstation computers. In 1980,
Microsoft announced its first Unix for 16-bit microcomputers called
Xenix, which the
Santa Cruz Operation ported to the
Intel 8086 processor in 1983, and eventually branched Xenix into
SCO UNIX in 1989.
In 1984, an industry group called X/Open was formed, with the aim of forming compatible open systems, that is, standardizing the UNIX environment. By the mid-1980s, the incompatibilities between competing versions of Unix, popularly called "the
Unix wars," were seen as hindering the adoption of Unix in a marketplace that was beginning to be dominated by
Microsoft's operating systems. Inspired to some extent by the development of dual-mode versions of Unix, the
IEEE Working Group P1003 developed the first POSIX standard for a Unix-based application programming interface, published in 1988.
AT&T added various features into UNIX System V, such as file locking, system administration,
streams, the Remote File System and TLI. AT&T cooperated with Sun Microsystems and between 1987 and 1989 merged features from
Xenix, BSD, SunOS, and System V into
System V Release 4 , independently of X/Open. This new release consolidated all the previous features into one package, and heralded the end of competing versions. It also increased licensing fees.
1990s
In 1990, the Open Software Foundation released OSF/1, their standard Unix implementation, based on Mach and BSD. The Foundation was started in 1988 and was funded by several Unix-related companies that wished to counteract the collaboration of AT&T and Sun on SVR4. Subsequently, AT&T and another group of licensees formed the group "UNIX International" in order to counteract OSF. This escalation of conflict between competing vendors gave rise to the phrase "
Unix wars".
In 1991, a group of BSD developers left the University of California to found Berkeley Software Design, Inc . BSDI produced a fully-functional commercial version of BSD Unix for the inexpensive and ubiquitous Intel platform, which started a wave of interest in the use of inexpensive hardware for production computing. Shortly after it was founded, Bill Jolitz left BSDI to pursue distribution of 386BSD, the free software ancestor of
FreeBSD,
OpenBSD, and
NetBSD.
By 1993 most of the commercial vendors of Unix had changed their commercial variants of Unix to be based on
System V with many BSD features added on top. The creation of the COSE initiative that year by the major players in Unix marked the end of the most notorious phase of the Unix wars, and was followed by the merger of UI and OSF in 1994. The new combined entity, which retained the OSF name, stopped work on OSF/1 that year. By that time the only vendor using it was
Digital, which continued its own development, rebranding their product Digital UNIX in early 1995.
Shortly after UNIX System V Release 4 was produced, AT&T sold all its rights to UNIX to Novell.
In 1993, Novell decided to transfer the UNIX
trademark and certification rights to the X/Open Consortium. In 1996, X/Open merged with OSF, creating the Open Group. Various standards by the Open Group now define what is and what is not a "UNIX" operating system, notably the post-1998 Single UNIX Specification.
In 1995, the business of administration and support of the existing UNIX licenses plus rights to further develop the System V code base were sold by Novell to the Santa Cruz Operation. Whether Novell also sold the copyrights is currently the subject of litigation .
2000 to present
In 2000, SCO sold its entire UNIX business and assets to Caldera Systems, which later on changed its name to The SCO Group. This new player then started a huge legal campaign against various users and vendors of Linux. The SCO Group has offered various legal theories over the course of several cases. Some of these allege that Linux contains copyrighted Unix code now owned by The SCO Group. Others allege trade-secret violations by
IBM, or contract violations by former Santa Cruz customers who have since converted to Linux. The most far-reaching theory is that development work that IBM did for AIX is considered a derivative work and therefore also owned by SCO. If this is upheld it would affect all Unix licensees.
Under a program called SCOsource, the SCO Group is now offering licenses to all companies and individuals wishing to use operating systems with code based on UNIX System V Release 4 .
However, Novell disputed the SCO group's claim to hold copyright on the UNIX source base. According to Novell, SCO are effectively franchise operators for Novell, which also retained the core copyrights, veto rights over future licensing activities of SCO, and 95% of the licensing revenue. The SCO Group disagreed with this, and the dispute had resulted in the SCO v. Novell lawsuit.
In 2005,
Sun Microsystems released the bulk of its Solaris system code into an
open source project called OpenSolaris. New Sun OS technologies such as the ZFS file system are now first released as open source code via the OpenSolaris project;
as of 2006 it has spawned several non-Sun distributions such as Jörg Schilling's SchilliX.
The
Dot-com crash has led to significant consolidation of Unix users as well. Of the many commercial flavors of Unix that were born in the 1980s, only HP-UX, AIX and
Solaris are still doing relatively well in the market.
Standards
Beginning in the late 1980s, an open operating system standardization effort now known as POSIX provided a common baseline for all operating systems;
IEEE based POSIX around the common structure of the major competing variants of the Unix system, publishing the first POSIX standard in 1988. At around the same time a separate but very similar standard, the Single UNIX Specification, was also produced by the Open Group. Starting in 1998 these two standards bodies began work on merging the two standards, and they are now identical.
In an effort towards compatibility, several Unix system vendors agreed on SVR4's Executable and Linkable Format as standard for binary and object code files. The common format allows substantial binary compatibility among Unix systems operating on the same CPU architecture.
The directory layout of some systems, particularly on Linux, is defined by the Filesystem Hierarchy Standard. This type of standard however is controversial, and even within the Linux community its adoption is far from universal.
Components
The Unix system is composed of several components that are normally packaged together. By including — in addition to the kernel of an operating system — the development environment, libraries, documents, and the portable, modifiable source-code for all of these components, Unix was a self-contained software system. This was one of the key reasons it emerged into an important teaching and learning tool and had such a broad influence.
Inclusion of these components did not make the system large — the original V7 Unix distribution, consisting of copies of all of the compiled binaries plus all of the source code and documentation occupied less than 10Mb, and arrived on a single 9-track magtape. The printed documentation was contained in two fairly thin books.
The names and filesystem locations of the Unix components has changed substantially across the history of the system. Nonetheless, the V7 implementation is considered by many to have the canonical early structure:
- Kernel — originally found in /usr/sys, and composed of several sub-components:
- conf — originally found in /usr/sys/conf, and composed of configuration and machine-dependent parts, often including boot code
- dev — Device drivers for control of hardware
- sys — The "kernel" of the operating system, handling memory management, system calls, etc.
- h — Header files, generally defining key interfaces within the system, and important system-specific invariables
- Development Environment — Most implementations of Unix contained a development environment sufficient to recreate the system from source code. The development environment included:
- cc — The C language compiler
- as — The machine-language assembler for the machine
- ld — The linker, for combining object files
- lib — Libraries. Originally libc, the system library with C run-time support, was the primary library, but there have always been additional libraries for such things as mathematical functions or database access. V7 Unix introduced the first version of the modern "Standard I/O" library stdio as part of the system library. Later implementations multiplied the number and type of libraries significantly.
- include — Header files for software development, defining standard interfaces and system invariants
- Other languages — V7 Unix contained a Fortran-77 compiler, a programmable calculator, and the awk "scripting" language, and other versions and implementations have or now contain many other language compilers and toolsets.
- ... and a number of other tools, including an object-code archive manager , symbol-table lister, compiler-development tools , make, and debugging tools.
- Commands — Most Unix implementations make little distinction between commands for system operation and maintenance , commands of general utility , and more general-purpose applications such as the text formatting and typesetting package. Nonetheless, some major categories are:
- sh — The Shell, the primary user-interface on Unix before window systems appeared, and the center of the command environment. To degrees that varied in different shell implementations, external programs were relied on by the shell.
- Utilities — the core of the Unix command set, including ls, grep, find and many others. This category could be subcategorized:
- System utilities — such as mkfs, fsck, and many others; and
- User utilities — passwd, kill, and others
- Document formatting — Unix systems were used from the outset for document preparation and typesetting systems, and included many related programs such as nroff, troff, tbl, eqn, refer, and pic
- Graphics — The plot subsystem provided facilities for producing simple vector plots in a device-independent format, with device-specific interpreters to display such files
- Communications — early Unix systems contained no inter-system communication, but did include the inter-user communication programs mail and talk. V7 introduced the early inter-system communication system UUCP, and systems beginning with the BSD release included TCP/IP utilities
- Documentation — Unix was unique in its time for including all of its documentation online in machine-readable form. The documentation included:
- man — Manual pages for each command, library component, system call, header file, etc.
- doc — Longer documents detailing major subsystems, such as the C language and troff
Impact
The Unix system had a great impact on other operating systems. Unix has been called "the most important operating system you may never use."
Following the lead of Multics, it was written in high level language as opposed to assembly .
It had a drastically simplified file model compared to many contemporary operating systems, treating all kinds of files as simple byte arrays. The file system hierarchy contained machine services and devices , providing a uniform interface, but at the expense of occasionally requiring additional mechanisms such as ioctl and mode flags to access features of the hardware that did not fit the simple "stream of bytes" model. The
Plan 9 operating system pushed this model even further and eliminated the need for additional mechanisms.
Unix also popularized the hierarchical file system with arbitrarily nested
subdirectories, originally introduced by Multics. Other common operating systems of the era had ways to divide a storage device into multiple directories or sections, but they were a fixed number of levels and often only one level. The major proprietary operating systems all added recursive subdirectory capabilities also patterned after Multics. DEC's RSTS programmer/project hierarchy evolved into
VMS directories,
CP/M's volumes evolved into
MS-DOS 2.0+ subdirectories, and HP's MPE group.account hierarchy and IBM's
System 36 and
OS/400 library systems were folded into broader POSIX file systems.
Making the command interpreter an ordinary user-level program, with additional commands provided as separate programs, was another Multics innovation popularized by Unix. The
Unix shell used the same language for interactive commands as for scripting . Since the shell and OS commands were "just another program", the user could choose his/her own shell. Finally, new commands could be added without
recompiling the shell. Unix's innovative command-line syntax for creating chains of producer-consumer processes made a powerful programming technique widely available. Many later command-line interpreters have been more or less inspired by the Unix shell.
A fundamental simplifying assumption of Unix was its focus on ASCII text for nearly all of its file formats. There were no "binary" editors in the original version of Unix — the entire system was configured using textual shell command scripts. The common denominator in the I/O system is the byte — unlike "record-based" file systems in other computers. The focus on text for representing nearly everything made Unix pipes useful. The focus on text and bytes made the system far more scalable and portable than other systems. Over time text-based applications have also won in application areas, such as printing languages , and when feasible, at the application layer of the Internet Protocols, i.e. Telnet, FTP, SMTP, HTTP, SIP, XML, etc.
Unix popularised a syntax for regular expressions that found much wider use. The Unix programming interface became the basis for a standard operating system interface .
The
C programming language, now ubiquitous in systems and applications programming, originated under Unix, and spread more quickly than Unix.
Early Unix developers were important in bringing the theory of modularity and reusability into
software engineering practice.
Unix provided the TCP/IP networking protocol on relatively inexpensive computers, which contributed to the
Internet explosion of world-wide real-time connectivity. This also exposed numerous security holes in its networking implementations, which formed the basis for implementations on many other platforms.
Over time, the leading developers of Unix developed a set of cultural norms for developing software, norms which became as important and influential as the technology of Unix itself; this has been termed the Unix philosophy.
2038
Unix stores time values as the number of seconds from midnight January 1 1970 in variables of type
time_t, historically defined as "signed 32-bit integer". On January 19 2038, the current time will roll over from a zero followed by 31 ones to a one followed by 31 zeros, which will reset time to the year 1901 or 1970, depending on implementation. As many applications use OS library routines for date calculations, the impact of this could be felt much earlier than 2038; for instance, 30-year mortgages may be calculated incorrectly beginning in the year 2008.
Since times before 1970 are rarely represented in Unix time, one possible solution that is compatible with existing binary formats would be to redefine
time_t as "unsigned 32-bit integer". However, such a kludge merely postpones the problem to February 72106, and would introduce bugs in software that needed to compare differences between two sets of time.
Some Unix versions have already addressed this. For example, in Solaris on 64-bit systems, time_t is 64 bits long, meaning that the OS itself and 64-bit applications will correctly handle dates through and beyond the year 292000000000. Existing 32-bit applications using a 32-bit time_t continue to work on 64-bit Solaris systems but are still prone to the 2038 problem.
Free Unix-like operating systems
In 1983,
Richard Stallman announced the GNU project, an ambitious effort to create a
free software Unix-like system; "free" in that everyone who received a copy would be free to use, study, modify, and redistribute it. GNU's goal was achieved in 1992. Its own kernel development project,
GNU Hurd, had not produced a working kernel, but a compatible kernel called
Linux was released as free software in 1992 under the
GNU General Public License. The combination of the two is frequently referred to simply as "Linux", although the Free Software Foundation and some Linux distributions, such as
Debian GNU/Linux, use the combined term
GNU/Linux. Work on GNU Hurd continues, although very slowly.
In addition to their use in the Linux operating system, many GNU packages — such as the
GNU Compiler Collection , the GNU C library and the GNU core utilities — have gone on to play central roles in other free Unix systems as well.
Linux distributions, comprising Linux and large collections of compatible software have become popular both with hobbyists and in business. Popular distributions include
Red Hat Enterprise Linux,
SUSE Linux,
Mandriva Linux,
Fedora Core, Ubuntu,
Debian GNU/Linux and Gentoo.
A free derivative of
BSD Unix, 386BSD, was also released in 1992 and led to the
NetBSD and
FreeBSD projects. With the 1994 settlement of a lawsuit that UNIX Systems Laboratories brought against the University of California and Berkeley Software Design Inc. , it was clarified that Berkeley had the right to distribute BSD Unix — for free, if it so desired. Since then, BSD Unix has been developed in several different directions, including the
OpenBSD and
DragonFly BSD variants.
Linux and the BSD kin are now rapidly occupying the market traditionally occupied by proprietary UNIX operating systems, as well as expanding into new markets such as the consumer desktop and mobile and embedded devices. A measure of this success may be seen when
Apple Computer sought out a new foundation for its Macintosh operating system: it chose
NEXTSTEP, an operating system developed by
NeXT with a freely redistributable core operating system, renamed Darwin after Apple acquired it. It was based on the BSD family and the Mach kernel. The deployment of Darwin BSD Unix in
Mac OS X makes it, according to a statement made by an Apple employee at a
USENIX conference, the most widely-used Unix-based system in the
desktop computer market. Due to the modularity of the Unix design, sharing bits and pieces is relatively common; consequently, most or all Unix and Unix-like systems include at least some BSD code, and modern BSDs also typically include some GNU utilities in their distribution, so Apple's combination of parts from NeXT and FreeBSD with Mach and some GNU utilities has precedent.
Branding
In October 1993, Novell, the company that owned the rights to the Unix System V source at the time, transferred the
trademarks of Unix to the X/Open Company , and in 1995 sold the related business operations to
Santa Cruz Operation. Whether Novell also sold the
copyrights to the actual software is
currently the subject of litigation in SCO v. Novell.
By decree of The Open Group, the term "UNIX" refers more to a class of operating systems than to a specific implementation of an operating system; those operating systems which meet The Open Group's Single UNIX Specification should be able to bear the UNIX 98 or UNIX 03 trademarks today, after the operating system's vendor pays a fee to The Open Group. Systems licensed to use the UNIX® trademark include AIX, HP-UX,
IRIX, Solaris, Tru64,
A/UX and a part of
z/OS. Apple Computer have stated that they will be submitting Mac OS X Server 10.5 to The Open Group for certification as a UNIX 03 system.
In practice, the term, especially when written as "
Un*x", "*NIX", or "*N?X" is applied to a number of other multiuser POSIX-based systems such as GNU/Linux, Mac OS X and FreeBSD that do not seek UNIX branding because the royalties would be too expensive for a product marketed to consumers or freely available over the Internet; this would mean that "Unix" has become a label for a variety of products, much like a genericized trademark. To avoid this, The Open Group requests that "UNIX" is always used as an adjective followed by a generic term such as "system".
The term "Unix" is also used, and in fact was the original capitalisation, but the name UNIX stuck because, in the words of
Dennis Ritchie "when presenting the original Unix paper to the third Operating Systems Symposium of the American
Association for Computing Machinery, we had just acquired a new typesetter and were intoxicated by being able to produce small caps" . Additionally, it should be noted that many of the operating system's predecessors and contemporaries used all-uppercase lettering, because many computer terminals of the time could not produce lower-case letters, so many people wrote the name in upper case due to force of habit.
Several plural forms of Unix are used to refer to multiple brands of Unix and Unix-like systems. Most common is the conventional "
Unixes", but the hacker culture which created Unix has a penchant for playful use of language, and "
Unices" is also popular. The
Anglo-Saxon plural form "Unixen" is not common, although occasionally seen.
Common Unix commands
Widely used Unix commands include:
- Directory and file creation and navigation: ls cd pwd mkdir rm rmdir cp find touch
- File viewing and editing: more ed vi emacs ex
- Text processing: echo cat grep sort uniq sed awk tail tee head cut tr split printf
- File comparison: comm cmp diff patch
- Miscellaneous shell tools: yes test xargs
- System administration: chmod chown ps su w who
- Communication: mail telnet ftp finger ssh
- Shells: sh bash
...
csh
ksh tcsh
The 60 user commands from section 1 of the First Edition were:
ar as b bas bcd
boot cat
chdir check chmod chown cmp cp date db dbppt dc df dsw dtf du ed find for form hup lbppt ld ln ls
mail mesg mkdir mkfs mount mv nm od pr rew rkd rkf rkl rm rmdir roff sdate
sh stat strip su sum tap tm tty type un wc who write
For a more complete and modern list, see the list of Unix programs.
List of Unix systems
Each version of the
UNIX Time-Sharing System evolved from the version before, with version one evolving from the prototypal
Unics. Not all variants and descendants are displayed.
Research Unix
- }}" align="" valign="" |
- Ken's new system
- UNIX Time-Sharing System v1
- UNIX Time-Sharing System v2
- UNIX Time-Sharing System v3
- UNIX Time-Sharing System v4
- UNIX Time-Sharing System v5
- UNIX Time-Sharing System v6
| width="" align="" valign="" |
- UNIX Time-Sharing System v7
- UNIX Time-Sharing System v8
- UNIX Time-Sharing System v9
- UNIX Time-Sharing System v10
|}
After the release of Version 10, the Unix research team at
Bell Labs turned its focus to
Plan 9 from Bell Labs, a distinct operating system that was first released to the public in 1993.
AT&T UNIX Systems and descendants
Each of the systems in this list is evolved from the version before, with
Unix System III evolving from both the
UNIX Time-Sharing System v7 and the descendants of the
UNIX Time-Sharing System v6.
- }}" align="" valign="" |
- Unix System III
- Unix System IV
- Unix System V
- Unix System V Release 2
- Unix System V Release 3.0
- Unix System V Release 3.2
- Unix System V Release 4
- Unix System V Release 4.2
| width="" align="" valign="" |
- UnixWare 7
- UnixWare 7.1
- UnixWare 7.1.1
- UnixWare NSC 7.1+IP
- UnixWare NSC 7.1+LKP
- UnixWare NSC 7.1DCFS
- Open Unix 8
- Open Unix 8MP1
- Open Unix 8MP2
- Open Unix 8MP3
- Open Unix 8MP4
- SCO UnixWare 7.1.3
- SCO UnixWare 7.1.3 Update Pack 1
- SCO UnixWare 7.1.4
|}
References
External links
- by Ian F. Darwin and Geoffrey Collyer
- -- The Open Group UNIX System Homepage
- Softpanorama Unix history page
- -- The Unix Acronym List
- A large graphical family tree of Unixes
