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GNU/Linux is fashioned on Unix. Unix dates from 1969 when Ken Thompson
at Bell Telephone Laboratories initiated work on this new operating
system. Others involved in the project included Dennis Ritchie and
Brian Kernighan. The name Unix is a pun on an alternative operating
system of the time called MULTICS (MULTiplexed Information and
Computing Service). MULTICS was developed by The Massachusetts
Institute of Technology, General Electric and Bell Labs. Unix was
originally spelt UNICS, an acronym for UNiplexed Information and
Computing Service!
Some of the basic ideas introduced by Multics and then Unix were the
tree structured file system, a program for command interpretation
(called the shell), the structure and nature of text files and the
semantics of I/O operations. Some of the philosophy that rose with the
development of Unix included the desire to write programs that
performed one task and to do it well, to write programs that worked
together to perform larger tasks, and to write programs that
communicated with each other using text from one program to the other.
The advantages of Unix were quickly identified by many and quite a few
varieties of Unix emerged over time. Sun Microsystems have pioneered
many of the developments in Unix, followed by such greats as the old
Digital Equipment Corporation (DEC, which was swallowed by Compaq,
which was swallowed by Hewlett-Packard), Silicon Graphics Incorporated
(SGI), International Business Machines (IBM), and Hewlett-Packard
(HP). A variety of flavours have existed, including SunOS, Solaris,
Ultrix, Irix, BSD, System V, HPUX, and so on. Although computer
programs written for one version of Unix could sometimes be ported to
other versions, it was not always an easy task. The diversity of Unix
implementations (more so than the proprietary nature of most of them)
made it difficult for Unix to become a commodity operating system.
The GNU project worked hard to free software development from nuances
of each of the different Unix versions through providing a common
programming language environment (GNU C) and a sophisticated packaging
tool (autoconf and automake) to carefully hide the
differences. GNU/Linux has now become the most popular Unix variant
and all the major Unix players support GNU/Linux in some way.
A particularly touted feature of Unix comes from a tools
philosophy where complex tasks are performed by bringing together a
collection of simpler tools. This is contrasted with the philosophy of
providing monolithic applications that in one fell swoop solve all
your problems, supposedly. The reality is often different.
Most operating systems supply a collection of basic utility programs
for managing your files (things like arranging your files into
folders, trashing files, and copying files from one place to another).
Large applications then provide the word processing, spreadsheet, and
web browsing functionality.
Unix places less emphasis on the monolithic applications. Instead,
tools provide simple functionality, focusing on doing well what they
are designed to do. They simply pass their results on to another tool
once they're done. Unix pipes provide the mechanism for doing
this: one tool pipes its output on to another tool. This allows
complex actions to be performed by piping together a collection of
simpler commands.
A typical example is to determine the number of users logged on to
your system:
The who command will list, one per line, each user logged
on. The wc command will count the number of characters,
words, and lines that it comes across, with the -l option
only counting the number of lines. (GNU tools, like Unix, introduce
options with the minus sign.)
For various reasons though this tools philosophy was often overlooked
when large monolithic applications arose that did not adhere to the
philosophy--they did not share components. Common tools such as
Netscape, ghostview, Acrobat, FrameMaker, and OpenOffice essentially
share very little. Compare that with the Microsoft community where,
for example, an application like Internet Explorer is component-based.
This is now changing in the GNU world with the operating system
software and the Gnome project encouraging component-based
architectures.
Another feature of Unix is that Unix applications tend to use open
file formats allowing a variety of tools to collaborate to work on
those open formats. Indeed, this has been a key in recent developments
to remove the strangle-hold of Microsoft proprietary formats. Rather
than electronic document storage providing a longer term solution to
the archival of documents, it is delivering an even shorter lifetime
than paper-based archives! How can that be so? The formats created by
proprietary software are often binary and not fully publicly
specified. How many packages today can read old Word Perfect and
MS Word documents? The standardisation on open formats, often
text-based formats like XML that allow anyone to read them, provides a
solution to this problem.
So why Unix? It is a conceptually simple operating system
facilitating creativity by not restricting the developer. Many have
found it to be a fun operating system to work with allowing many
innovative developments to be combined in new and even more innovative
ways to deliver powerful ideas. A very large world wide group of
people willingly provide excellent, free support over the Internet.
Anyone can learn more about the operating system by studying the code
itself. Anyone can contribute to porting the operating system to
their favourite computer.
And finally, the much touted stability. There is very little doubt
that GNU and Linux are extremely stable. The habit of rebooting your
computer every time you come back to it is something Microsoft seems to
encourage because of it's notorious instability and tendency for the
operating system not to carefully manage its use of memory. Also,
install a new package under MS/Windows and chances are you need to
reboot the computer. Most Unix users rarely need to reboot their
machine. Check the uptime and you will generally find the
machine has not been rebooted for months or years. Installing
packages invariably does not require rebooting. Indeed, the
only time it does is when you upgrade your Linux kernel!
Copyright © 1995-2006 [email protected]
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