The UNIX FAQ
What is UNIX?
UNIX is the name of an operating system which began development at Bell Labs in 1969, led by Ken Thompson and Dennis Ritchie. This name is also used to collectively refer to all operating systems built on similar principles. The name is pronounced /'junəks/, like the word “eunuchs,” but its original name, Unics, was short for the “UNiplexed Information and Computer Service.”
The term “UNIX-like” is often used to describe OSs that are built on similar principles to UNIX, but either are not certified as an official UNIX version by the Open Group, who owns the trademark, or cannot be traced directly back to Bell Labs. To be clear, Dennis Ritchie did not hold to such a strict definition of UNIX.
How has UNIX become so prominent among operating systems?
There were four major factors which contributed to the spread of UNIX in its early days.
Unlike many OSs of the era, the earliest versions of UNIX included a hierarchical file system, which included folders and subfolders. Even MS-DOS as late as 1983 lacked such a feature.
Early UNIX programmers at Bell Labs championed a philosophy whereby every program was devoted to one task, and doing it well. One might select certain segments of a file (grep), while one show the results of systematically altering a file (sed). This is related to the use of the UNIX pipeline, which allowed the output of one program to be used as the input of another, without having to save this output temporarily to (then) precious hard drive space.
The C language was invented to write UNIX code. As the 1970s rolled on, increasing portions of the system code for UNIX was written in C rather than processor-specific machine language, allowing it to be ported across a diverse set of computer architectures.
Finally, Bell Labs’ parent company, AT&T, had been in hot water with the US federal government for monopolistic practices. As part of an agreement with Washington, AT&T was not permitted to enter industries that were not strictly related to the telephone business. AT&T cautiously avoided entering the computing industry and charged clients for installation fees of UNIX alone. This was a double-edged sword, as AT&T did not help maintain clients’ UNIX installations. This necessitated custom bug fixes and add-ons to UNIX among its userbase.
What is Linux, and what is its relation to UNIX?
To explain Linux, one must explain what exactly an OS and a kernel are. An operating system is a special kind of powerful computer program that controls the resources of other computer programs and directly interfaces with a computer’s hardware. The portion of an OS that interfaces with hardware is called the kernel.
A number of attempts throughout the 1980s were made to get UNIX onto home computers, few with lasting success. Being written in C rather than machine code meant UNIX could be easily ported to different computers, but required way more resources from a CPU, which the i386 processor found on many home computers had difficulties keeping up with.
One such attempt was MINIX. A student at the University of Helsinki named Linus Torvalds found MINIX to be fairly usable, but had some objections to its kernel’s design, and created his own kernel. After some coaxing by friends of his, he named the kernel Linux and eventually released it as open-source software. This allowed others to use it as the basis of various operating systems. An OS using the Linux kernel is called a Linux distribution.
Linux is not, and never has been, the entirety of any OS. It is strictly a kernel used to create UNIX-like OSs. When its name is discussed among complete OSs, it is generally being used collectively to refer to the OSs which utilize its kernel.
Is it possible to use UNIX without a command line?
If you use any current Apple product or almost any smartphone, you already do. When Steve Jobs left Apple in 1985, he founded NeXT, which sold UNIX workstations. Apple bought NeXT when they needed Steve Jobs back at the helm and rebranded the particular UNIX-like system on NeXT computers as OS X, later macOS. Other Apple products use OSs based on early macOS versions. This is besides the existence of various Linux distributions that include a GUI. Many people, who are either tired of the constant, long software updates for Windows or are concerned about its backdoors, switch to one of these distributions and never once use the command line. In addition, Android’s OS is based on the Linux kernel.
What does open-source mean? What does it mean that Linux is “free?”
Open-source software has had its source code released willingly by its developers to the general public, to be viewed and (if so desired) altered. It is synonymous with the term “free software,” as used by computing professionals. The terms are indeed confusing, which has prompted programmer Richard Stallman to humorously clarify that “free software” means, “‘Free’ as in speech, not beer.” In practice, almost no free software costs anything to acquire or use. The technical term for software whose source code cannot be freely viewed by the general public but does not cost anything is freeware. Chrome is freeware, while Firefox is free software.
Doesn’t the fact that anyone can view the source code for Linux make it more vulnerable to hackers?
Not at all. At any point, hundreds of people are watching the source code for various Linux distributions like a hawk. If a security flaw is found, whoever finds it will sound the alarm, allowing it to be patched. By contrast, proprietary OSs might have flaws that are not monitored closely by their developers (and some which are exploited by corporations and governments to spy on users), and thus are not patched.
What are the practical uses for UNIX? Besides Apple products, are any UNIX-like systems used by more than a niche quorum of computer nerds?
UNIX-like systems have had a constant presence in servers and businesses worldwide since the 1970s. Almost any company you can name has a UNIX installation for their servers. Almost any current movie or TV show you watch was composited and rendered on a machine running a UNIX-like system. Almost every website is hosted on a UNIX-like system. Embedded UNIX systems are found in everything from airplanes to modems.
As mentioned earlier in the FAQ, UNIX began development in 1969, and development was relatively decentralized from an early period. By contrast, besides small fragments of MS-DOS code, current versions of Windows have been based primarily on Windows NT, which began development in 1993, and whose source code has always been closed off to the public. This means that UNIX has had almost a quarter of a century more time to mature as a family of OSs, meaning that it was a force to be reckoned with far earlier than Windows, so much so that Microsoft has spent fortunes in a panic trying to stifle its proliferation, as evidenced by the Halloween Documents.
0 notes