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I could have a three-letter acronym, for Something's Not UNIX
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Alix, a name that fit perfectly with the Unix developer conven-
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" Because the woman was a Unix system administrator, Stallman says it would have been an even more touching tribute
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identical to Unix," the author wrote
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mersed himself in the world of Unix software development
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Unix, on the other
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Simply put, what the Unix approach
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the Unix community as well
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On Unix systems it was a crippling barrier, since the machines
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Within the Unix community, the two nat-
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In rewriting Emacs for the Unix audience, Stallman stood a
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The Unix market that had seemed so collegial even at
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to Unix source code, a trend that only speeded the number of
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The Unix wiz-
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sion of Unix, is technically a competitor to the GNU/Linux op-
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Unix systems and Unix-related offshoots, the primary competit-
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company's in-house version of Unix
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late 1970s and was responsible for many key parts of Unix, in-
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tions that already had a Unix source license from AT&T
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ship of the Unix brand name-the effort would finally bear fruit
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gramming to Unix, using the university's MicroVAX
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log in to his Unix account, Torvalds quickly began looking for a
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Unix variant a name that ended with the letter X
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In fact, he had all but shunned the renegade operating system when it first appeared on the Unix programming landscape in 1991
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System V, which was the inferior version of Unix
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the hacker best known for his work on Electric Fence, a Unix
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was picking up steam in the commercial Unix marketplace
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North Carolina, a Unix company billing itself as Red Hat was
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tury of Unix , issued a call for papers to members of the GNU
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The unix timestamp for the date the user was
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The written string is stored in the variable $start_date, which is then passed to strtotime(), which in turn returns the Unix timestamp for the start of the month
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The string is then passed to strtotime($end_date), which gives us the Unix timestamp for the end of the month; this value is stored in the variable $end_of_month
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php file and pass to it some dates (as a Unix timestamp) for the helper to convert
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Why time() + 30? Well, time() is the php function that returns the Unix timestamp for "now" (whenever "now" is for you), and the + 30 is 30 seconds added to the current timestamp value returned by time(), meaning "now plus 30 seconds" (or "30 seconds in the future")
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All these systems ran the original Bell Labs Unix Operating System, which included the first Windows-type software called xt-layers
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Minicomputers and the Rise of UNIX
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The UNIX operating system was developed at AT&T Bell Laboratories in the 1970s
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Since it was written in a high level language, when that language was ported to a new machine architecture UNIX was also able to be ported
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The system is an example of a system which started as a database application support program, graduated to system work, and still exists across a wide variety of systems supported on most UNIX systems as an addon database system
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"I'll think about Unix programming source code if you don't mind
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"I'm jealous of that Unix programming source code
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The UNIX operating system was developed in the 60’s and 70’s
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Unix is used by both
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that are unique to all UNIX systems
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The operating system under UNIX consists of many of the
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Ironically, the importance of the UNIX
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As we said, UNIX is used as a basis for other operating systems
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Unix” which was chosen because while it is Unix based, it is freeware
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The standard tool for this on Unix and Windows systems is a character-based utility called route (in Unix) or route
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Most of the Unix operating systems support SMP, including Linux versions as well as Mac
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If you have Unix systems on your network, however, you are more likely to use DNS to identify them using names, and in this case, you must create resource records for them
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One of the most common SMTP servers used on the Internet is a free Unix program called sendmail, but there are many other products, both open source and commercial, that run on a variety of computing platforms
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Developed as a college project by Linus Torvalds of Sweden, the Linux operating system has emerged as one of the most popular Unix variants
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One of the biggest advantages of Linux over other Unix variants is its excellent driver support
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Device drivers are an integral part of any operating system, and if Unix is ever going to become a rival to Windows in the personal computer mainstream, it’s going to have to run on the same computers that run Windows, using the same peripherals
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Many of the other Unix variants have relatively limited device driver support
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If you are trying to install a Unix product on an Intel-based computer with the latest and greatest video adapter, for example, you may not be able to find a driver that takes full advantage of its capabilities
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One of the best features of a Linux (or Unix) file is that it can be edited while it is open
59.
Unix is a multiuser, multitasking operating system (OS) with roots that date back to the late 1960s
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It was developed throughout the 1970s by researchers at AT&T’s Bell Labs, finally culminating in Unix System V Release 1 in 1983
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During this time, and since then, many other organizations have built their own variants on the Unix formula, and now dozens of different operating systems function using the same basic Unix components, including both Apple and Linux
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This was possible because, from the beginning, Unix has been more of a collaborative research project than a commercial product
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While some companies guard the source code to their operating systems, many Unix developers make their code freely available
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Unix is not a user-friendly OS, nor is it commonly found on the desktop of the average personal computer user
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To its detractors, Unix is an outdated OS that relies primarily on an archaic, character-based interface
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To its proponents, however, Unix is the most powerful, flexible, and stable OS available
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More than other operating systems, Unix is based on a principle of simplicity that makes it highly adaptable to many different needs
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This is not to say that Unix is simple to use because generally it isn’t
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For example, a Unix system treats physical devices in the computer, such as the printer, the keyboard, and the display, in the same way as it treats the files and directories on its drives
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Another fundamental principle of Unix is the use of small, simple tools that perform specific functions and that can easily work together with other tools to provide more complex functions
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Instead of large applications with many built-in features, Unix operating systems are far more likely to utilize a small tool that provides a basic service to other tools
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DOS can use pipes to redirect standard input and output in various ways, but Unix includes a much wider variety of tools and commands that can be combined to provide elaborate and powerful functions
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Thus, Unix is based on relatively simple elements, but its ability to combine those elements makes it quite complex
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While a large application attempts to anticipate the needs of the user by combining its functions in various predetermined ways, Unix supplies users with the tools that provide the basic functions and lets them combine the tools to suit their own needs
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The various Unix operating systems are built around basic elements that are fundamentally the same, but they include various collections of tools and programs
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However, one of the other principles of Unix development that has endured through the years is the custom of making the source code for Unix software freely available to everyone
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The result of this open source movement is a wealth of Unix tools, applications, and other software that is freely available for download from the Internet
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In some cases, programmers modify existing Unix modules for their own purposes and then release those modifications to the public domain so that they can be of help to others
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Some programmers collaborate on Unix software projects as something of a hobby and release the results to the public
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One of the best examples of this is the Linux operating system, which was designed from the beginning to be a free product and which has now become one of the most popular Unix variants in use today
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No matter what hardware a Unix system uses, the basic software components are the same (see Figure 20-1)
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Unlike Windows, which limits you to a single command interpreter, Unix traditionally has several shells you can choose from, with different capabilities
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The shells that are included with particular Unix operating systems vary, and others are available as free downloads
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The original Unix shell is a program called sh that was created by Steve Bourne and is commonly known as the Bourne shell
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• csh Known as the C shell and originally created for use with Berkeley Software Distribution (BSD) Unix; utilizes a syntax similar to that of the C language and introduces features such as a command history list, job control, and aliases
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Unix includes hundreds of small programs, usually called tools or commands, which you can combine on the command line to perform complex tasks
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Unix command-line tools are programs, but don’t confuse them with the complex applications used by other operating systems, such as Windows
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Unix has full-blown applications as well, but its real power lies in these small programs
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Adding a new tool on a Unix system does not require an installation procedure; you simply have to specify the appropriate location of the tool in the file system in order for the shell to run it
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The sheer number of Unix variants can be bewildering to anyone trying to find the appropriate operating system for a particular application
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However, apart from systems intended for special purposes, virtually any Unix OS can perform well in a variety of roles, and the selection you make may be based more on economic factors, hardware platform, or personal taste than on anything else
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If, for example, you decide to purchase proprietary Unix workstations, you’ll be using the version of the OS intended for the machine
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If you intend to run Unix on Intel-based computers, you might choose the OS based on the GUI that you feel most comfortable with, or you might be looking for the best bargain you can find and limit yourself to the versions available as free downloads
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The following sections discuss some of the major Unix versions available
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Unix System V is the culmination of the original Unix work begun by AT&T’s Bell Labs in the 1970s
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2, the project was wholly developed by AT&T, even while other Unix work was ongoing at the University of California at Berkeley and other places
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Unix System V Release 4 (SVR4), released in the late 1980s, consolidated the benefits of the SVR operating system with those of Berkeley’s BSD, Sun’s SunOS, and Microsoft’s Xenix
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This release brought together some of the most important elements that are now indelibly associated with the name Unix, including networking elements such as the TCP/IP Internet Package from BSD, which includes file transfer, remote login, and remote program execution capabilities, and the Network File System (NFS) from SunOS
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In 1975, one of the original developers of Unix, Ken Thompson, took a sabbatical at the University of California at Berkeley, and while there, he ported his current Unix version to a PDP-11/70 system
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The seed he planted took root, and Berkeley became a major developer of Unix in its own right
