1965年時，貝爾實驗室(Bell Labs)加入一項由奇異電子(General Electric)和麻省理工學(xué)院(MIT)合作的計畫；該計畫要建立一套多使用者、多任務(wù)、多層次(multi-user、multi-processor、multi-level)的MULTICS操作系統(tǒng)。直到1969年，因MULTICS計畫的工作進度太慢，該計畫就被停了下來。當(dāng)時，Ken Thompson（后被稱為Unix之父）已經(jīng)有一個稱為「星際旅行」的程序在GE-635的機器上跑，但是反應(yīng)非常的慢，正巧也被他發(fā)現(xiàn)了一部被閑置的PDP-7(Digital的主機)，Ken Thompson和Dernis Ritchie就將「星際旅行」的程序移植到PDP-7上。而這部PDP-7就此在整個計算機歷史上留下了芳名。
MULTICS 其實是”MULTiplexed Information and Computing System”的縮寫，在1970年時，那部PDP-7卻只能支持兩個使用者，當(dāng)時，Brian Kernighan 就開玩笑地戲稱他們的系統(tǒng)其實是：”UNiplexed Information and Computing System”，縮寫為”UNICS”，后來，大家取其諧音，就稱其為”Unix”了。1970年可稱為是Unix元年。
1971年，他們申請了一部PDP-11/20，申請的名義是：要發(fā)展文書處理系統(tǒng)。該提案被獲采納，他們也發(fā)展出了一套文書處理系統(tǒng) ─ 就是現(xiàn)在Unix操作系統(tǒng)里面文書處理系統(tǒng)(nroff/troff)的前身。有趣的是，沒有多久，貝爾實驗室的專利部門真的采用了這套系統(tǒng)作為他們處理文件的工具，而貝爾實驗室的專利部門也就順理成章地成為Unix的第一個正式使用者。當(dāng)時，那部PDP-11／20只有0.5MB磁盤空間。而描述這整個系統(tǒng)的文件被標示為：”First Edition”，版本日期是1970年11月。從此以后，Unix的版本就以系統(tǒng)文件的版別來稱呼。
UNIX家譜
UNIX的歷史開始于1969年ken Thompson，Dennis Ritchie（即著名的K&G，C語言的發(fā)明人）與一群人在一部PDP-7上進行的一些工作，后來這個系統(tǒng)變成了UNIX。它主要的幾個版本為：
V1（1971）：第一版的UNIX，以PDP-11/20的匯編語言寫成。包括文件系統(tǒng)，fork、roff、ed等軟件。
V4（1973）：以C語言從頭寫過，這使得UNIX修改容易，可以在幾個月內(nèi)移植到新的硬件平臺上。最初C語言是為UNIX設(shè)計的，所以C與UNIX間有緊密的關(guān)系。
V6（1975）：第一個在貝爾實驗室外（尤其是大學(xué)中）廣為流傳的UNIX版本。這也是UNIX分支的起點與廣受歡迎的開始。1.xBSD （PDP-II）就是由這個版本衍生出來的。
V7（1979）：在許多UNIX玩家的心目中，這是“最后一個真正的UNIX，”這個版本包括一個完整的K&RC編譯器，Bourne shell。V7移植到VAX機器后稱為32V。
目前開發(fā)UNIX（System V）的公司是Unix System Laboratories (USL)。USL本為AT&T所有，1993年初被Novell收購。Novell于1993年末將UNIX這個注冊商標轉(zhuǎn)讓給X/Open組織。
目前為止，UNIX有兩大流派：那就是AT&T發(fā)布的UNIX操作系統(tǒng)System V與美國加州大學(xué)伯克利分校發(fā)布的UNIX版BSD（Berkeley Software Distribution）。SVR4是兩大流派融合后的產(chǎn)物。1991年底，與System V針鋒相對的開放軟件基金會(Open Software Foundation)推出了OSF/1。
現(xiàn)在幾種主要的UNIX版本：
* AIX：IBM的UNIX，是根據(jù)SVR2（最近已經(jīng)出到SVR3.2）以及一部分BSD延伸而來，加上各種硬件的支持。具備特有的系統(tǒng)管理（SMIT）。
* 386BSD：Jolitz從Net/2 software移植過來的。支持Posix，32位。
* FreeBSD：1.x從386BSD 0.1而來，F(xiàn)reeBSD 2.x版是用4.4BSD lite改寫。
* HP-UX（HP）：舊系統(tǒng)是從S III（SVRx）發(fā)展面來，現(xiàn)在是由SVR2（4.2BSD）發(fā)展而來，目前是10.x版。
* Linux(x86)：遵從POSIX，SYSV及BSD的擴展，這一點從上頁表中即可看出。
* OSF/1（DEC）：DEC對OSF/1的移植。
* SCO UNIX（x86）：SVR3.2，目前影響較大的PC UNIX。
* SunOS（680×0，Sparc，i386）：根據(jù)4.3BSD，包含許多來自System V的東西。Sun的主要成果在于：NFS，OpenLook GUI標準，現(xiàn)演變?yōu)镾olaris 。
* Ultrix(DEC)：根據(jù)4.2BSD再加上許多4.3BSD的東西。
* Xenix(x86)：Intel硬件平臺上的UNIX，以SVR2為基礎(chǔ)，由微軟推出。在中國使用較廣泛。
| Year | Event |
| 1957 | Bell Labs found they needed an operating system for their computer center which at the time was running various batch jobs. The BESYS operating system was created at Bell Labs to deal with these needs. |
| 1965 | Bell Labs was adopting third generation computer equipment and decided to join forces with General Electric and MIT to create Multics (Multiplexed Information and Computing Service). |
| 1969 | By April 1969, AT&T made a decision to withdraw Multics and go with GECOS. When Multics was withdrawn Ken Thompson and Dennis Ritchie needed to rewrite an operating system in order to play space travel on another smaller machine (a DEC PDP-7 [Programmed Data Processor 4K memory for user programs). The result was a system which a punning colleague called UNICS (UNiplexed Information and Computing Service)–an ’emasculated Multics’. |
| 1969 | Summer 1969 UNIX was developed. |
| 1969 | Linus Torvalds is born. |
| 1971 | First edition of UNIX released 11/03/1971. The first edition of the “UNIX PROGRAMMER’S MANUAL [by] K. Thompson [and] D. M. Ritchie” is also dated “November 3, 1971”. It includes over 60 commands like: b (compile B program); boot (reboot system); cat (concatenate files); chdir (change working directory); chmod (change access mode); chown (change owner); cp (copy file); ls (list directory contents); mv (move or rename file); roff (run off text); wc (get word count); who (who is one the system). The main thing missing was pipes. |
| 1972 | Second edition of UNIX released 12/06/1972 |
| 1972 | Ritchie rewrote B and called the new language C. |
| 1973 | UNIX had been installed on 16 sites (all within AT&T/Western Electric); it was publically unveiled at a conference in October. |
| 1973 | Third edition of UNIX released February 1973 |
| 1973 | Forth edition of UNIX released November 1973 |
| 1974 | Fifth edition of UNIX released June 1974 |
| 1974 | Thompson went to UC Berkeley to teach for a year, Bill Joy arrived as a new graduate student. Frustrated with ed, Joy developed a more featured editor em. |
| 1975 | Sixth edition of UNIX released May 1975 |
| 1975 | Bourne shell is introduced begins being added onto. |
| 1977 | 1BSD released late 1977 |
| 1978 | 2BSD released mid 1978 |
| 1979 | Seventh edition of UNIX released January 1979 |
| 1979 | 3BSD released late 1979 |
| 1979 | SCO founded by Doug and Larry Michels as UNIX porting and consulting company. |
| 1980 | 4.0BSD released October 1980 |
| 1982 | SGI introduces IRIX. |
| 1983 | SCO delivers its first packaged UNIX system called SCO XENIX System V for Intel 8086 and 8088 processor-based PCs. |
| 1984 | Ultrix 1.0 was released. |
| 1985 | Eighth edition of UNIX released February 1985 |
| 1985 | The GNU manifesto is published in the March 1985 issue of Dr. Dobb’s Journal. The GNU project starts a year and a half later. |
| 1986 | HP-UX 1.0 released. |
| 1986 | Ninth edition of UNIX released September 1986 |
| 1987 | Sun and AT&T lay the groundwork for business computing in the next decade with an alliance to develop UNIX System V Release 4. |
| 1988 | HP-UX 2.0 released. |
| 1988 | HP-UX 3.0 released. |
| 1989 | SCO ships SCO UNIX System V/386, the first volume commercial product licensed by AT&T to use the UNIX System trademark. |
| 1989 | HP-UX 7.0 released. |
| 1989 | Tenth edition of UNIX released October 1989 |
| 1990 | AIX short for Advanced Interactive eXecutive was first entered into the market by IBM February 1990. |
| 1991 | Sun unveils Solaris 2 operating environment, specially tuned for symetric multiprocessing. |
| 1991 | Linux is introduced by Linus Torvalds, a student in Finland. Who post to the comp.os.minix newsgroup with the words: Hello everybody out there using minix – I’m doing a (free) operating system (just a hobby, won’t be big and professional like gnu) for 386(486) AT clones. |
| 1991 | HP-UX 8.0 released. |
| 1991 | BSD/386 ALPHA First code released to people outside BSDI 12/xx/1991 |
| 1992 | HP-UX 9.0 released. |
| 1993 | NetBSD 0.8 released 04/20/1993 |
| 1993 | FreeBSD 1.0 released December of 1993 |
| 1994 | Red Hat Linux is introduced. |
| 1994 | Caldera, Inc was founded in 1994 by Ransom Love and Bryan Sparks. |
| 1994 | NetBSD 1.0 released 10/26/1994 |
| 1995 | FreeBSD 2.0 released 01/xx/1995 |
| 1995 | SCO acquires UNIX Systems source technology business from Novell Corporation (which had acquired it from AT&T’s UNIX System Laboratories). SCO also acquires UnixWare 2 operating system from Novell. |
| 1995 | HP-UX 10.0 released. |
| 1995 | 4.4 BSD Lite Release 2 the true final distribution from the CSRG 06/xx/1995 |
| 1997 | HP-UX 11.0 released. |
| 1997 | Caldera ships OpenLinux Standard 1.1 May 5, 1997, the second offering in Caldera’s OpenLinux product line |
| 1998 | IRIX 6.5 the fifth generation of SGI UNIX is released July 6, 1998. |
| 1998 | SCO delivers UnixWare 7 operating system. |
| 1998 | Sun Solaris 7 operating system released. |
| 1998 | FreeBSD 3.0 released 10/16/1998 |
| 2000 | FreeBSD 4.0 released 03/13/2000 |
| 2000 | Caldera Systems Inc. announces that Caldera Systems has entered into agreement to acquire the SCO Server Software Division and the Professional Services Division |
