Unix
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, such as contributors to the
GNU project.
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 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 (an issue that is currently being decided in court). Only systems fully compliant with and certified to the
Single UNIX Specification qualify as "UNIX" (others are called "UNIX system-like" or
Unix-like).
During the late 1970s and early 1980s, Unix's influence in academic circles led to massive adoption (particularly of the
BSD variant, originating from the
University of California, Berkeley) of Unix by commercial startups, the most notable of which is
Sun Microsystems.
Sometimes,
Traditional Unix may be used to describe a Unix or
GNU operating system that has the characteristics of either
Version 7 Unix or
UNIX System V.
 |
Filiation of Unix and Unix-like systems. |
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. GNU/
Linux, a Unix inspired operating system available for free and from commercial distributors, is gaining popularity as an alternative to proprietary operating systems like
Microsoft Windows.
Unix is written in C. 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."
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 (
Multiplexed
Information and
Computing
Service), 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 go in scarce computing time. [
1]
|
A partial list of simultaneously-running processes on a Unix system. The processes can be manipulated by their number (left column) using the kill command. The second column shows which computer terminal the process is running on (or ?? if independent of a terminal). The third column contains status information. The fourth is the amount of CPU time the process has used. The rest is the command line, as entered at the shell prompt or script. The dollar sign at the bottom of the screen is a prompt for the next command. |
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 (thus becoming portable), 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 (the
Lions' Commentary on UNIX 6th Edition, with Source Code), which led to considerable adoption of Unix as an educational operating system.
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. V5 and especially V6 led to a plethora of different Unix versions both inside and outside Bell Labs, including
PWB/UNIX,
IS/1 (the first commercial Unix), and the
University of Wollongong's port to the
Interdata 7/32 (the first non-PDP Unix).
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
|
Editing a shell script using the 'ed' editor. The dollar-sign at the top of the screen is the prompt printed by the shell. 'ed' was typed there to start the editor. The editor takes over from that point on the screen, downwards. On old Unix systems, this was the entire screen, not just one window. |
AT&T now developed
UNIX System III, based on Version 7, as a commercial version and sold the product directly, the first version launching in 1982. However its subsidiary,
Western Electric, continued to sell older Unix versions, based on the UNIX System (Versions 1 to 7). To end the confusion between all the differing versions, AT&T combined various versions developed at other universities and companies into
UNIX System V Release 1. This introduced 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.
The new commercial Unix releases however no longer included the source code and so the Berkeley researchers continued to develop BSD Unix as an alternative to UNIX System III and V, originally on the PDP-11 architecture (the 2.xBSD releases, ending with 2.11BSD). 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 ("Tahoe" being the nickname of the CCI Power 6/32 architecture that was the first non-DEC port of the BSD kernel), Net/1, 4.3BSD-Reno (to match the "Tahoe" naming, and that the release was something of a gamble), 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. Others chose BSD instead. One of the leading developers of BSD,
Bill Joy, went on to co-found
Sun Microsystems in 1982 and create
SunOS (now
Solaris) for their
workstation computers. In 1980,
Microsoft announced its first Unix for
16-bit microcomputers called
Xenix, which the
Santa Cruz Operation (SCO) 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, standardize the UNIX systems.
AT&T added various features into UNIX System V, such as
file locking,
system administration,
job control (modelled on
ITS),
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 (SVR4), independently of X/Open. This new release consolidated all the previous features into one package, and threatened the end of competing versions. It also greatly increased licensing fees.
1990s
|
The Common Desktop Environment or CDE, a graphical desktop for Unix co-developed in the 1990s by HP, IBM, and Sun as part of the COSE initiative. |
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 (Donn Seeley, Mike Karels, Bill Jolitz, and Trent Hein) left the University of California to found Berkeley Software Design, Inc (
BSDI). 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. (Dennis Ritchie likened this to the Biblical story of
Esau selling his birthright for the proverbial "
mess of pottage". [
2]) Novell developed its own version,
UnixWare, merging its
Netware with UNIX System V Release 4. Novell tried to use this to battle against
Windows NT, but their core markets suffered considerably.
In 1993, Novell decided to transfer the UNIX
trademark and certification rights to the
X/Open Consortium.[
3] 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.[
4] Whether Novell also sold the copyrights is currently the subject of litigation (see below).
2000 to present
|
A modern Unix desktop environment. |
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 (and their own release, UNIX System V, Release 5).
However, Novell disputed the SCO group's claim to hold copyright on the UNIX source base. According to Novell, SCO (and hence the SCO Group) 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.
Beginning in the late 1980s, an open operating system standardization effort known as
POSIX provided a common baseline for all operating systems;
IEEE based POSIX around the structure of the Unix system. 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 the latest revisions of both are in fact identical.
In an effort towards compatibility, several Unix system vendors agreed on SVR4's
ELF 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 among many, and even within the Linux community adoption is far from universal.
The Unix system is composed of several components that are normally packaged together. By including 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 (originally /usr/sys/dev) for control of hardware (and sometimes pseudo-hardware)
*
sys -- The "kernel" of the operating system, handling memory management, system calls, etc
*
h (or
include) -- 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 linking loader for combining object files
*
lib -- Libraries. Originally
libc, the C runtime library, was the primary library, but there have always been additional libraries for (e.g.) floating-point emulation (
libm) or a database implementation. V7 Unix introduced the first consistent "Standard I/O" library
stdio. Later implementations multiplied the number and type of libraries significantly.
*
include -- Header files for software development, defining standard interfaces and system invariants
**Other (secondary) languages -- V7 Unix contained a Fortran-77 compiler, 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 (
ar), symbol-table lister, compiler-development tools (e.g.
yacc),
make, and debugging tools.
*
Commands -- Most Unix implementation make little distinction between commands (user-level programs) for system operation and maintenance (e.g.
cron), commands of general utility (e.g.
grep), 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 (such as
expr) 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
*
Runoff -- Unix systems never lost their heritage as early document preparation and typesetting systems, and included many related programs such as
troff,
tbl,
neqn,
refer,
plot *
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
|
The 'man' command can display a 'man page' for every command on the system, including itself. |
*
Documentation -- While not strictly part of the operating system, 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,
troff, and other systems.
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 (assembly had been necessary for achieving acceptable performance on early computers).
It had a drastically simplified file model compared to many contemporary operating systems. The file system hierarchy contained machine services and devices (such as
printers,
terminals, or
disk drives), providing a superficially uniform interface, but at the expense of requiring indirect mechanisms such as
ioctl and mode flags to access features of the hardware that did not fit the simple "stream of bytes" model.
Unix also popularized the hierarchical file system with arbitrarily nestedsubdirectories, 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 (
shell scripts -- there was no separate job control language, like IBM's
JCL for example). Since the shell and OS commands were "just another program", the user could choose (or even write) 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 (pipes) made a powerful programming technique (
coroutines) widely available.
A fundamental simplifying assumption of Unix was its focus on ASCII text for 100% of its I/O package and the assumption that the machine word was a multiple of 8 bits in size. There were no "binary" editors in the original version of Unix - the entire system was configured using text shell commands and the least and greatest common denominator in the I/O system is the text byte - unlike "record-based" file systems in other computers. The focus on text for representing "everything" made Unix pipes useful. The focus on text and 8-bit 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 (
PostScript - not
InterPress - an earlier effort by the same people), 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 (POSIX, see above).
The
C programming language, now ubiquitous in systems and applications programming, originated under Unix, and spread more quickly than Unix. The C language was the first agnostic language that did not attempt to force a coding style upon the programmer (e.g. support for 3 types of loops and all types of parameter passing.) The C language was the first programming language to access a computer's full instruction set (e.g. masking, shifting, auto increment, auto decrement, jump tables, pointers.) However, the unsafeness of C leads to problems such as
buffer overflows from C library functions such as
gets() and
scanf(), which are behind many notorious bugs, including one exploited by the
Morris worm.
Early Unix developers were important in bringing the theory of
software modularity and
re-use into
engineering practice.
Unix provided the TCP/IP networking protocol on relatively inexpensive computers, which later resulted in the
Internet explosion of world-wide real-time connectivity. This quickly exposed several major security holes in the Unix architecture, kernel, and system utilities.
Over time, the leading developers of Unix (and programs that ran on it) developed a set of cultural norms for developing software, norms which became as important and influential as the technology of Unix itself. See
Unix philosophy for more information.
2038
Unix stores time values as the number of seconds from midnight
January 1,
1970 (the "
Unix Epoch") in variables of size 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.
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.
|
Linux is a modern Unix-like system |
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 â€" such as the
GNU Compiler Collection (and the rest of the
GNU toolchain), the
GNU C library and the
GNU core utilities â€" 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 Linux,
SUSE Linux,
Mandriva Linux,
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. (
USL v. BSDi), it was clarified that Berkeley had the right to distribute BSD Unix â€" 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.
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 (now
The Open Group),[
5] and in 1995 sold the related business operations to
Santa Cruz Operation.[
6] 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.
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, FreeBSD, NetBSD, OpenBSD 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; such systems claim that the term has now become 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" (quoted from the
Jargon File, version 4.3.3, 20 September 2002). 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
culture that created Unix has a penchant for playful use of language, and "
Unices" (treating Unix as
Latin word) is also popular. The
Anglo-Saxon plural form "Unixen" is not common, although occasionally seen.
The most basic Unix commands and utilities are:
*Directory and file creation and navigation:
ls cd pwd mkdir rm rmdir cp find*File viewing and editing:
touch 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*Misc shell tools:
yes test xargs*System administration:
chmod chown ps su w who*Communication:
mail telnet ftp finger ssh*Shells:
sh bash csh ksh tcshThese are the 60 user commands from section 1 of the First Edition:
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 writeFor a more complete and modern list, see the
list of Unix programs.
This is a
list of Unixes (sing. Unix). 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
:
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.
:
*Unix System III (1981)
*Unix System IV (1982)
*Unix System V (1983)
**Unix System V Release 2 (1984)
**Unix System V Release 3.0 (1986)
**Unix System V Release 3.2 (1987)
**Unix System V Release 4 (1988)
**Unix System V Release 4.2 (1992)
*UnixWare 1.1 (1993)
**UnixWare 1.1.1 (1994)
*UnixWare 2.0 (1995)
**UnixWare 2.1 (1996)
***UnixWare 2.1.2 (1996) |
*UnixWare 7 (System V Release 5) (1998)
**UnixWare 7.0.1 (1998)
*UnixWare 7.1 (1999)
**UnixWare 7.1.1 (1999)
**UnixWare NSC 7.1+IP (2000)
**UnixWare NSC 7.1+LKP (2000)
**UnixWare NSC 7.1DCFS (2000)
*Open Unix 8 (UnixWare 7.1.2) (2001)
**Open Unix 8MP1 (2001)
**Open Unix 8MP2 (2001)
**Open Unix 8MP3 (2002)
**Open Unix 8MP4 (2002)
*SCO UnixWare 7.1.3 (2002)
**SCO UnixWare 7.1.3 Update Pack 1 (2003)
**SCO UnixWare 7.1.4 (2004) |
* Ritchie, D.M.; Thompson, K., The UNIX Time-Sharing System (The Bell System Technical Journal, July-August 1978, Vol. 57, No. 6, Part 2)
*
Salus, Peter H.:
A Quarter Century of UNIX, Addison Wesley, June 1, 1994; ISBN 0201547775
*
*
Ancient UNIX Systems -- older versions of Unix, now available under an
open source license
*
Plan 9 from Bell Labs, the successor of Unix developed at
Bell Labs by
Ken Thompson,
Rob Pike and others.
*
Inferno, a Plan 9-like Operating System originally developed at Bell Labs.
*
OpenSolaris, the
open source codebase for Sun's
Solaris operating system, based on Unix System V Release 4
*
BSD licenseLions' Commentary on UNIX 6th Edition, with Source Code documents the 6th edition of Unix.
*
Unix pipes
**
Filter (Unix)**
Pipeline (Unix)*
Rare mode*
Single UNIX SpecificationUNIX-HATERS Handbook*Unix devices
**
/dev/null - the 'bit bucket'
**
/dev/urandom and
/dev/random - hardware random number generators
**
/dev/zero - a zero generator
*
Unix-like**
GNU**
GNU Hurd**
Cygwin**
Linux**
MinGW**
Minix**
SOX Unix**further
BSD descendants*
List of Unix daemons*
Unix manual*
Unix wars*
Computer term origins*
Comparison of file systems*
Open system*
Open standard*
Open format*
Vendor lock-in*
Embrace, extend and extinguish*
Network effect*
Unix shells*
What is UNIX, Anyway?*
The Creation of the UNIX Operating System*
Over 50 flavors of Unix @ Unix Guru Universe*
Unix heritage (more links)*
UNIX Evolution (
PostScript) by Ian F. Darwin and Geoffrey Collyer
*
Unix @ dmoz.org*http://www.UNIX-systems.org/ --
The Open Group UNIX System Homepage
*
Unix History with Some Emphasis on Scripting Softpanorama Unix history page
*http://www.roesler-ac.de/wolfram/acro/index.htm -- The Unix Acronym List
*
The Unix Tree*
Ancient UNIX*
Unix As Literature*
Unix History A large graphical family tree of Unixes
zh-yue:UNIX
