1．What is an UNIX
An operating system originally developed by Dennis Ritchie and Ken Thompson at AT&T Bell Laboratories that allows a computer to handle multiple users and programs simultaneously．Since its development in the early 1970s，UNIX has been enhanced by many individuals and particularly by computer scientists at the University of Uantornia，Berkeley（known as Berkeley Software Distribution UNIX，or BSD UNIX）．This operating system is available on a wide variety of computer systems，ranging from personal computers to mainframes，and is available in other related forms．AIX is in implementation that runs on IBM workstations，A/UX is a graphical version that runs on Macintosh computers；Solaris runs on Intel microprocessors．UnixWare is the Novell implementation of UNIX．NetWare for UNIX is an Original Equipment Manufacturer（OEM）version of NetWare that can run on a UNIX host．

2．The UNIX System Can Support Many Users
Depending on the machine being used，a UNIX system can support from one to over one hundred users，each concurrently running a different set of programs．The cost of a computer that can be used by many people at the same time is less per user than that of a computer that can be used by only a single person at a time．[1] The cost is less because one person cannot generally use all of the resources a computer has to offer．No one can keep the printer going constantly，keep all the system memory in use，keep the disk busy reading and writing，keep the tape drives spinning，keep the modem in use，and keep the terminals busy．[2] A multiuser operating system allows many people to use all of the system resources almost simultaneously．Thus，utilization of costly resources can be maximized，and the cost per user can be minimized．These are the primary objectives of a multiuser operating system．
3．The UNIX System Can Support Many Tasks
The UNIX operating system allows each user to run more than one job at a time．You can run several jobs

UNIX操作系統(tǒng)
1．什么是UNIX操作系統(tǒng)
UNIX操作系統(tǒng)最早是由美國電話電報(bào)公司（AT&T）貝爾實(shí)驗(yàn)室的丹尼斯•里奇和肯• 湯普森開發(fā)的，它允許計(jì)算機(jī)同時處理多用戶和程序。從20世紀(jì)70年代開發(fā)以來，UNIX經(jīng)由許多個人和公司，特別是加利福尼亞大學(xué)伯克利分校的計(jì)算機(jī)科學(xué)家的努力而得到增強(qiáng)（通常稱為伯克利軟件發(fā)行部UNIX或BSD UNIX）。這種操作系統(tǒng)在各類計(jì)算機(jī)系統(tǒng)，即從個人計(jì)算機(jī)到大型機(jī)上廣泛使用，并可以其他相關(guān)形式使用。AIX是運(yùn)行在IBM工作站上的版本；A/UX 是在Macintosh計(jì)算機(jī)上運(yùn)行的圖形版本；Solaris是在英特爾微處理器上運(yùn)行的版本；UnixWare是UNIX的Novell實(shí)現(xiàn)。 UNIX的Net-Ware是可以在UNIX主機(jī)上運(yùn)行的NetWare原始設(shè)備制造商（OEM）版本。
2．UNIX系統(tǒng)能支持多用戶
與所使用的機(jī)器有關(guān)，UNIX系統(tǒng)可以支持一個用戶到上百個用戶，每個用戶都并發(fā)地運(yùn)行一組不同的程序。由很多人同時使用一臺計(jì)算機(jī)的人均成本比一次只允許一個人使用一臺計(jì)算機(jī)的成本要低。成本低是因?yàn)橐粋€人不能總是使用計(jì)算機(jī)的所有資源：沒有一個人總是占用打印機(jī)，占用系統(tǒng)全部內(nèi)存，總是使磁盤忙于讀寫，使磁帶驅(qū)動器一直轉(zhuǎn)動，一直占用modem，總使終端忙碌；一個多用戶操作系統(tǒng)允許很多人幾乎同時使用所有的系統(tǒng)資源。因此，使昂貴資源的利用率達(dá)到最高，戶均費(fèi)用最小，這就是多用戶操作系統(tǒng)的主要目標(biāo)。