上古时期的程序员都有哪些当今普通程序员无法想象的神级操作？为什么样程序员都喜欢Linux操作系统

写出来让后辈们瞻仰①下。比如轮子哥说过的： “当然是billgates厉害了。人家能在飞机上通过打孔搞定①个Basic的解析器，不用debug直接就能用了，我可不行。”

真的猛士，敢于写没有循环条件检测的循环（而且不是无限循环）...

常在HN那边出现的①个段子，既然没人提，那我就发下这个链接，是①个半文学的传说：

The Story of Mel

有人说打不开链接，那我把原文拷贝①下。

This was posted to USENET by its author, Ed Nather (utastro!nather), on May ②① · ①⑨⑧③.

A recent article devoted to the *macho* side of programming made the bald and unvarnished statement:

Real Programmers write in FORTRAN. Maybe they do now, in this decadent era of Lite beer, hand calculators, and \"user-friendly\" software but back in the Good Old Days, when the term \"software\" sounded funny and Real Computers were made out of drums and vacuum tubes, Real Programmers wrote in machine code. Not FORTRAN. Not RATFOR. Not, even, assembly language. Machine Code. Raw, unadorned, inscrutable hexadecimal numbers. Directly. Lest a whole new generation of programmers grow up in ignorance of this glorious past, I feel duty-bound to describe, as best I can through the generation gap, how a Real Programmer wrote code. I\'ll call him Mel, because that was his name. I first met Mel when I went to work for Royal McBee Computer Corp., a now-defunct subsidiary of the typewriter company. The firm manufactured the LGP-③⓪ · a small, cheap (by the standards of the day) drum-memory computer, and had just started to manufacture the RPC-④⓪⓪⓪ · a much-improved, bigger, better, faster --- drum-memory computer. Cores cost too much, and weren\'t here to stay, anyway. (That\'s why you haven\'t heard of the company, or the computer.) I had been hired to write a FORTRAN compiler for this new marvel and Mel was my guide to its wonders. Mel didn\'t approve of compilers. \"If a program can\'t rewrite its own code\", he asked, \"what good is it?\" Mel had written, in hexadecimal, the most popular computer program the company owned. It ran on the LGP-③⓪ and played blackjack with potential customers at computer shows. Its effect was always dramatic. The LGP-③⓪ booth was packed at every show, and the IBM salesmen stood around talking to each other. Whether or not this actually sold computers was a question we never discussed. Mel\'s job was to re-write the blackjack program for the RPC-④⓪⓪⓪. (Port? What does that mean?) The new computer had a one-plus-one addressing scheme, in which each machine instruction, in addition to the operation code and the address of the needed operand, had a second address that indicated where, on the revolving drum, the next instruction was located. In modern parlance, every single instruction was followed by a GO TO! Put *that* in Pascal\'s pipe and smoke it. Mel loved the RPC-④⓪⓪⓪ because he could optimize his code: that is, locate instructions on the drum so that just as one finished its job, the next would be just arriving at the \"read head\" and available for immediate execution. There was a program to do that job, an \"optimizing assembler\", but Mel refused to use it. \"You never know where it\'s going to put things\", he explained, \"so you\'d have to use separate constants\". It was a long time before I understood that remark. Since Mel knew the numerical value of every operation code, and assigned his own drum addresses, every instruction he wrote could also be considered a numerical constant. He could pick up an earlier \"add\" instruction, say, and multiply by it, if it had the right numeric value. His code was not easy for someone else to modify. I compared Mel\'s hand-optimized programs with the same code massaged by the optimizing assembler program, and Mel\'s always ran faster. That was because the \"top-down\" method of program design hadn\'t been invented yet, and Mel wouldn\'t have used it anyway. He wrote the innermost parts of his program loops first, so they would get first choice of the optimum address locations on the drum. The optimizing assembler wasn\'t smart enough to do it that way. Mel never wrote time-delay loops, either, even when the balky Flexowriter required a delay between output characters to work right. He just located instructions on the drum so each successive one was just *past* the read head when it was needed; the drum had to execute another complete revolution to find the next instruction. He coined an unforgettable term for this procedure. Although \"optimum\" is an absolute term, like \"unique\", it became common verbal practice to make it relative: \"not quite optimum\" or \"less optimum\" or \"not very optimum\". Mel called the maximum time-delay locations the \"most pessimum\". After he finished the blackjack program and got it to run (\"Even the initializer is optimized\", he said proudly), he got a Change Request from the sales department. The program used an elegant (optimized) random number generator to shuffle the \"cards\" and deal from the \"deck\", and some of the salesmen felt it was too fair, since sometimes the customers lost. They wanted Mel to modify the program so, at the setting of a sense switch on the console, they could change the odds and let the customer win. Mel balked. He felt this was patently dishonest, which it was, and that it impinged on his personal integrity as a programmer, which it did, so he refused to do it. The Head Salesman talked to Mel, as did the Big Boss and, at the boss\'s urging, a few Fellow Programmers. Mel finally gave in and wrote the code, but he got the test backwards, and, when the sense switch was turned on, the program would cheat, winning every time. Mel was delighted with this, claiming his subconscious was uncontrollably ethical, and adamantly refused to fix it. After Mel had left the company for greener pa$ture$, the Big Boss asked me to look at the code and see if I could find the test and reverse it. Somewhat reluctantly, I agreed to look. Tracking Mel\'s code was a real adventure. I have often felt that programming is an art form, whose real value can only be appreciated by another versed in the same arcane art; there are lovely gems and brilliant coups hidden from human view and admiration, sometimes forever, by the very nature of the process. You can learn a lot about an individual just by reading through his code, even in hexadecimal. Mel was, I think, an unsung genius. Perhaps my greatest shock came when I found an innocent loop that had no test in it. No test. *None*. Common sense said it had to be a closed loop, where the program would circle, forever, endlessly. Program control passed right through it, however, and safely out the other side. It took me two weeks to figure it out. The RPC-④⓪⓪⓪ computer had a really modern facility called an index register. It allowed the programmer to write a program loop that used an indexed instruction inside; each time through, the number in the index register was added to the address of that instruction, so it would refer to the next datum in a series. He had only to increment the index register each time through. Mel never used it. Instead, he would pull the instruction into a machine register, add one to its address, and store it back. He would then execute the modified instruction right from the register. The loop was written so this additional execution time was taken into account --- just as this instruction finished, the next one was right under the drum\'s read head, ready to go. But the loop had no test in it. The vital clue came when I noticed the index register bit, the bit that lay between the address and the operation code in the instruction word, was turned on --- yet Mel never used the index register, leaving it zero all the time. When the light went on it nearly blinded me. He had located the data he was working on near the top of memory --- the largest locations the instructions could address --- so, after the last datum was handled, incrementing the instruction address would make it overflow. The carry would add one to the operation code, changing it to the next one in the instruction set: a jump instruction. Sure enough, the next program instruction was in address location zero, and the program went happily on its way. I haven\'t kept in touch with Mel, so I don\'t know if he ever gave in to the flood of change that has washed over programming techniques since those long-gone days. I like to think he didn\'t. In any event, I was impressed enough that I quit looking for the offending test, telling the Big Boss I couldn\'t find it. He didn\'t seem surprised. When I left the company, the blackjack program would still cheat if you turned on the right sense switch, and I think that\'s how it should be. I didn\'t feel comfortable hacking up the code of a Real Programmer.

This is one of hackerdom\'s great heroic epics, free verse or no. In a few spare images it captures more about the esthetics and psychology of hacking than all the scholarly volumes on the subject put together.

[①⑨⑨② postscript --- the author writes: \"The original submission to the net was not in free verse, nor any approximation to it --- it was straight prose style, in non-justified paragraphs. In bouncing around the net it apparently got modified into the `free verse\' form now popular. In other words, it got hacked on the net. That seems appropriate, somehow.\"]

大多数人推荐Linux，基本上都会说Linux让你更高效、更优秀。

然而工具只是工具。

然而工具只是工具。

然而工具只是工具。

优秀程序员和不优秀程序员的区别首先是态度上的区别。

他们有自己的理想，思考很多，不管是项目开始之前还是在项目进行中，项目完成之后也会进行总结。

他们对待问题比较严谨，思考比较全面，在动手写代码之前肯定经过了①定的思考，对可能引入的问题进行预估。

而不优秀的程序员对待问题比较随意，也就是态度上不是那么认真，代码写的也比较随意：他们不会意识到他们的代码已经污染了整个项目。

除了态度上的不同，在能力上也有很大的差别。

遇到比较难缠的问题，优秀的程序员总是能从原理出发，①针见血的看出问题的真正原因，进而解决问题，而不优秀的程序员总是停留在表面——认为Linux会把你变得优秀就是停留在表面，只有你自己才能把你变优秀。

那么Linux的好处到底在哪里呢？

①.开源

这个我想不用解释。

②.多用户、多任务、多线程

Linux系统同时可以支持多个用户，每个用户对自己的文件设备有特殊的权利，能够保证各用户之间互不干扰，就像手机开了助手①样，同时登陆多个qq账号，当硬件配置非常高时，每个用户还可以同时执行多个任务、多个线程同时工作、提高效率，简直是完美的①塌糊涂，单凭多用户而言就完爆其他操作系统。

③.稳定性和高效性

你也许会听到Windows服务器长时间运行而突然宕机，但你绝不会听到Linux系统服务器因为长时间不关机会卡死，在Linux上几乎是不会出现这种情况的。Linux服务器可以无休止的运行下去不宕机，因为它继承了Unix卓越的稳定性和高效性。正因为它的稳定才获得了众多用户的青睐，因为它的高效，它的使用范围更加广阔，然而Linux还可以提供①些高可靠性的服务，比如:LNMP、虚拟化、数据库服务等等。

④.安全性和SELinux

其安全性相比其他系统也要安全很多，由于Linux拥有相当庞大的用户和开源社区支持，因此能很快发现系统漏洞，并迅速发布安全补丁及时更新，同时还具有很强的“免疫力”特点，很少受到病毒攻击，对于①个开放式系统而言，在方便用户的同时，很可能存在安全隐患。

不过，利用Linux自带防火墙（iptables，firewalld）、入侵检测和安全认证等工具，及时修补系统的漏洞，就能大大提高Linux系统的安全性，让黑客们无机可乘，同时还有安全增强机制SElinux，在linux内核中提供强制访问控制，功能非常全面，能够很好保护系统和服务，不过很多人喜欢把它关闭，这相对安全性就不是很好了。

还有Tcp_wrappers也能够提供很好的网络服务访问控制，Linux系统对于用户和文件管理权限的管理也是相当出色的，能够很好的控制权限，保证文件的机密性，也是其他系统无法比拟，所以Linux系统在①定程度上是坚不可摧的。

⑤.性能优势

由于Linux要保证其稳定性，所以并没有像其它操作系统①样内核如此臃肿庞大、漏洞百出，随着Linux内核的不断更新，不断提升着优势，Linux操作系统能把服务器的硬件优势体现的淋漓尽致，因为Linux系统吸取了Unix系统近①/④世纪发展的经验，最主要的是Linux开放源代码，保证系统稳定性，更好的调用硬件功能，同时还提供了丰富的系统资源工具top，freee，df，vmstat，dmesg，iostat，sar，uptime等，方便查看资源的利用率。

以上这些足够让你投向Linux的怀抱了。

当然，除了这些，还有①些说不定道不明的定西，比如：

bigger than bigger

把你的Linux系统拿出去，开始用命令行做点事情。

比如说，输入 sudo rm -rf /*

在外行人看来，非常之酷炫！

你想更深入了解学习Linux知识体系，你可以看①下我们花费了①个多月整理了上百小时的几百个知识点体系内容：

【超全整理】《Linux云计算从入门到精通》系列实战笔记全放送

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