The Rise of Unix

The Rise of Unix

Far from the bright lights of the ARPAnet, off in the wilds of New Jersey, something else had been going on since 1969 that would eventually overshadow the PDP-10 tradition. The year of ARPAnet's birth was also the year that a Bell Labs hacker named Ken Thompson invented Unix.

Thompson had been involved with the development work on a time-sharing OS called Multics, which shared common ancestry with ITS. Multics was a test-bed for some important ideas about how the complexity of an operating system could be hidden inside it, invisible to the user, and even to most programmers. The idea was to make using Multics from the outside (and programming for it!) much simpler, so that more real work could get done.

Bell Labs pulled out of the project when Multics displayed signs of bloating into an unusable white elephant (the system was later marketed commercially by Honeywell but never became a success). Ken Thompson missed the Multics environment, and began to play at implementing a mixture of its ideas and some of his own on a scavenged DEC PDP-7.

Another hacker named Dennis Ritchie invented a new language called `C' for use under Thompson's embryonic Unix. Like Unix, C was designed to be pleasant, unconstraining, and flexible. Interest in these tools spread at Bell Labs, and they got a boost in 1971 when Thompson and Ritchie won a bid to produce what we'd now call an office automation system for internal use there. But Thompson & Ritchie had their eye on a bigger prize.

Traditionally, operating systems had been written in tight assembler to extract the absolute highest efficiency possible out of their host machines. Thompson and Ritchie were among the first to realize that hardware and compiler technology had become good enough that an entire operating system could be written in C, and by 1978 the whole environment had been successfully ported to several machines of different types.

This had never been done before, and the implications were enormous. If Unix could present the same face, the same capabilities, on machines of many different types, it could serve as a common software environment for all of them. No longer would users have to pay for complete new designs of software every time a machine went obsolete. Hackers could carry around software toolkits between different machines, rather than having to re-invent the equivalents of fire and the wheel every time.

Besides portability, Unix and C had some other important strengths. Both were constructed from a ``Keep It Simple, Stupid'' philosophy. A programmer could easily hold the entire logical structure of C in his head (unlike most other languages before or since) rather than needing to refer constantly to manuals; and Unix was structured as a flexible toolkit of simple programs designed to combine with each other in useful ways.

The combination proved to be adaptable to a very wide range of computing tasks, including many completely unanticipated by the designers. It spread very rapidly within AT&T, in spite of the lack of any formal support program for it. By 1980 it had spread to a large number of university and research computing sites, and thousands of hackers considered it home.

The workhorse machines of the early Unix culture were the PDP-11 and its descendant, the VAX. But because of Unix's portability, it ran essentially unaltered on a wider range of machines than one could find on the entire ARPAnet. And nobody used assembler; C programs were readily portable among all these machines.

Unix even had its own networking, of sorts—UUCP: low-speed and unreliable, but cheap. Any two Unix machines could exchange point-to-point electronic mail over ordinary phone lines; this capability was built into the system, not an optional extra. In 1980 the first Usenet sites began exchanging broadcast news, forming a gigantic distributed bulletin board that would quickly grow bigger than ARPAnet. Unix sites began to form a network nation of their own around Usenet.

A few Unix sites were on the ARPAnet themselves. The PDP-10 and Unix/Usenet cultures began to meet and mingle at the edges, but they didn't mix very well at first. The PDP-10 hackers tended to consider the Unix crowd a bunch of upstarts, using tools that looked ridiculously primitive when set against the baroque, lovely complexities of LISP and ITS. ``Stone knives and bearskins!'' they muttered.

And there was yet a third current flowing. The first personal computer had been marketed in 1975; Apple was founded in 1977, and advances came with almost unbelievable rapidity in the years that followed. The potential of microcomputers was clear, and attracted yet another generation of bright young hackers. Their language was BASIC, so primitive that PDP-10 partisans and Unix aficionados both considered it beneath contempt.

 

《黑客道简史》 第二章 Unix兴起

1969年，在ARPAnet光辉照耀不到的新泽西郊外，正有人在酝酿着什么，最终PDP-10的传统也将为此颠覆。ARPAnet诞生的那一年，贝尔实验室的黑客肯·汤普森（Ken Thompson）发明了Unix。

汤普森曾经参与了Multics的研发，这是一个与ITS拥有共同先祖[1]的分时操作系统。Multics可以说是一个试验台，通过它，人们尝试是否可以将复杂的操作系统（甚至是绝大部分程序）隐藏起来，不让用户直接接触。这样就能从外部简单的操控（甚至是编辑）Multics，这可谓是质的突破。[2]

当Multics变得臃肿并最终成为一个累赘的时候，贝尔实验室退出了（稍后，这个系统被霍尼韦尔公司推向了市场，但是没能成功）。在失去Multics作业环境之后，肯·汤普森找来了一台闲置的DEC PDP-7型计算机，打算在这上面将Multics的理念和自己的创想合二为一。

另一位叫丹尼斯·里奇（Dennis Ritchie）的黑客针对汤普森摇篮里的Unix开发了一种新的语言——C语言。如同Unix一样，C语言的设计非常出色，严谨而不失弹性。这些工具在贝尔实验室中流行开来，在大家的帮助下汤普森和里奇的申请终于在1971年得以通过。他们被授权为内部开发一套我们现在所说的“事务工作自动化系统”（office automation system）。[3]然而汤普森和里奇的雄心却远不止于此。

当时的传统观点认为，操作系统必须用严密的汇编程序编写，这样才能“榨干”主机得到最大效能。汤普森和里奇却相信，当时的硬件和编译器技术已经很成熟，足可以担负一个全部由C语言编写的操作系统了。终于，1978年Unix就已经可以成功的移植到多种机型上了。

这是史无前例，意义深远的。也就是说，如果Unix能在不同的机型上展现相同的界面和能力，它就可以被作为一个通用软件环境。用户需要每次为一种机型担负整套新软件的日子一去不复返了。黑客们可以将软件工具包移入不同的机器，这可比每次重新“生火、造轮子”要强得多了。

除了可移植性之外，Unix和C语言还有许多显著优势。它们都秉承了“KISS”设计哲学[4]。程序员可以轻松掌握C语言的逻辑结构（这与之前和之后的语言都大不一样），而不必整天翻阅用户指南。而Unix则可以看作是一个颇具弹性的工具包，由许多独立设计的程序有效地相互连接而成。

Unix和C语言应用范围之广，有时甚至是完全出乎设计者意料的。虽然没有什么正式的推广计划，但是它们还是迅速在AT&T内部传播开来。到了1980年，已经蔓延到为数众多的大学和计算研究机构，还有数以千计的黑客想把它们带回家。

早期Unix文化中的主力机型是PDP-11和其后裔——VAX。由于Unix具有高度的可移植性，所以能在为数众多的机器上原封不动的运行，而并不局限于那些接入ARPAnet的机器。[5]没人再用汇编程序了，C程序欣然进驻了所有机器。

Unix甚至有了自己的网络，各式各样的UUCP。[6]低速，不稳定却成本低廉。两台Unix机器可以通过普通的电话线相连，交换点对点电邮。这个功能并非一个可选组建，而是被写入了系统。1980年，第一个Usenet站点开始交换广播新闻[7]，借此形成的巨大的分布式电子公告板系统，将会迅速成长并超越ARPAnet。围绕Usenet，Unix站点开始形成了自己的网络疆域。

一些Unix站点本身是基于ARPAnet的。这样PDP-10和Unix/Usenet文化就开始在边缘交汇，融合。融合在一开始并不是一帆风顺的。PDP-10黑客把Unix用户视作是一堆暴发户，与LISP和ITS令人爱不释手的复杂华美相比，他们的工具简直原始到可笑。“刀耕火种的家伙”，他们嘟囔道。

除此之外，这里还有第三路人马。第一台个人电脑在1975年进入市场，1977年苹果公司成立，随后的几年里创新以几乎难以置信的速度喷涌而至。微型计算机的轮廓日渐明朗，这吸引到了另一代睿智的年青黑客。他们使用BASIC语言，无论是PDP-10游击队还是Unix信徒，在他们眼中都原始的不值一提。

 

 

 

 

 

 

 

 

1.这里是指“兼容分时系统”（Compatible Time-Sharing System，CTSS）。

2.也就是后台运行，而用户只需要使用命令。

3.这里是说贝尔实验室拨款给他们添置了一台 PDP-11/20

4.KISS是“Keep It Simple, Stupid”的缩写，即“务求简约”。

5.在这一时期，接入ARPAnet的主力机型也是PDP-11和VAX。

6.UUCP,UUCP是Unix-to-Unix Copy的缩写，是一组软件程序，所以说是“各式各样”的。

7.Usenet,又称友思网。是一种（最初）基于UUCP的世界性新闻组网络系统。广播新闻是指Usenet中的一个站点向网络（局域网或广域网）上所有其他站点发送消息。

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