英文文献原文译文--Linux

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1.1. History

1.1.1. UNIX

In order to understand the popularity of Linux, we need to travel back in time, about

30 years ago...

Imagine computers as big as houses, even stadiums. While the sizes of those computers

posed substantial problems, there was one thing that made this even worse: every

computer had a different operating system. Software was always customized to serve a

specific

purpose,

and

software

for

one

given

system

didn't

run

on

another

system.

Being

able

to

work

with

one

system

didn't

automatically

mean

that

you

could

work

with

another.

It was difficult, both for the users and the system administrators.

Computers were extremely expensive then, and sacrifices had to be made even after the

original purchase just to get the users to understand how they worked. The total cost

of IT was enormous.

Technologically the world was not quite that advanced, so they had to live with the

size for another decade. In 1969, a team of developers in the Bell Labs laboratories

started

working

on

a

solution

for

the

software

problem,

to

address

these

compatibility

issues. They developed a new operating system, which was

simple and elegant

written in the C programming language instead of in assembly code

able to recycle code.

The Bell Labs developers named their project

The

code

recycling

features

were

very

important.

Until

then,

all

commercially

available

computer systems were written in a code specifically developed for one system. UNIX

on

the

other

hand

needed

only

a

small

piece

of

that

special

code,

which

is

now

commonly

named the kernel. This kernel is the only piece of code that needs to be adapted for

every specific system and forms the base of the UNIX system. The operating system and

all other functions were built around this kernel and written in a higher programming

language,

C.

This

language

was

especially

developed

for

creating

the

UNIX

system.

Using

this new technique, it was much easier to develop an operating system that could run

on many different types of hardware.

The

software

vendors

were

quick

to

adapt,

since

they

could

sell

ten

times

more

software

almost effortlessly. Weird new situations came in existence: imagine for instance

computers from different vendors communicating in the same network, or users working

on

different

systems

without

the

need

for

extra

education

to

use

another

computer.

UNIX

did a great deal to help users become compatible with different systems.

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Throughout the next couple of decades the development of UNIX continued. More things

became possible to do and more hardware and software vendors added support for UNIX

to their products.

UNIX

was

initially

found

only

in

very

large

environments

with

mainframes

and

minicomputers

(note

that

a

PC

is

a

computer).

You

had

to

work

at

a

university,

for the government or for large financial corporations in order to get your hands on

a UNIX system.

But smaller computers were being developed, and by the end of the 80's, many people

had home computers. By that time, there were several versions of UNIX available for

the PC architecture, but none of them were truly free.

1.1.3. Current application of Linux systems

Today

Linux

has

joined

the

desktop

market.

Linux

developers

concentrated

on

networking

and services in the beginning, and office applications have been the last barrier to

be taken down. We don't like to admit that Microsoft is ruling this market, so plenty

of alternatives have been started over the last couple of years to make Linux an

acceptable

choice

as

a

workstation,

providing

an

easy

user

interface

and

MS

compatible

office applications like word processors, spreadsheets, presentations and the like.

On the server side, Linux is well-known as a stable and reliable platform, providing

database

and

trading

services

for

companies

like

Amazon,

the

well- known

online

bookshop,

US Post Office, the German army and such. Especially Internet providers and Internet

service

providers

have

grown

fond

of

Linux

as

firewall,

proxy-

and

web

server,

and

you

will find a Linux box within reach of every UNIX system administrator who appreciates

a comfortable management station. Clusters of

Linux machines are used

in the

creation

of movies such as

centers

that

route

mail

and

in

large

search

engine,

clusters

are

used

to

perform

internet

are

only

a

few

of the thousands

of heavy-duty

jobs that

Linux

is

performing day-to-day across the world.

It is also worth to note that modern Linux not only runs on workstations, mid- and

high-end servers, but also on

applications

and

even

on

experimental

wristwatches.

This

makes

Linux

the

only

operating

system in the world covering such a wide range of hardware.

1.2. The user interface

1.2.1. Is Linux difficult?

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Whether Linux is difficult to learn depends on the person you're asking. Experienced

UNIX

users

will

say

no,

because

Linux

is

an

ideal

operating

system

for

power-users

and

programmers, because it has been and is being developed by such people.

Everything

a

good

programmer

can

wish

for

is

available:

compilers,

libraries,

development

and

debugging

tools.

These

packages

come

with

every

standard

Linux

distribution. The C-compiler is included for free, all the documentation and manuals

are

there,

and

examples

are

often

included

to

help

you

get

started

in

no

time.

It

feels

like UNIX and switching between UNIX and Linux is a natural thing.

In the early days of Linux, being an expert was kind of required to start using the

system.

.

It

was

common

practice

to

tell

a

beginning

user

to

(read

the

manuals).

While the manuals were on every system, it was difficult to find the documentation,

and even if someone did, explanations were in such technical terms that the new user

became easily discouraged from learning the system.

The

Linux-using

community

started

to

realize

that

if

Linux

was

ever

to

be

an

important

player on the operating system market, there had to be some serious changes in the

accessibility of the system.

1.2.2. Linux for non-experienced users

Companies such as RedHat, SuSE and Mandrake have sprung up, providing packaged Linux

distributions

suitable

for

mass

consumption.

They

integrated

a

great

deal

of

graphical

user interfaces (GUIs), developed by the community, in order to ease management of

programs

and services. As a

Linux user

today you have all the means of getting to know

your system inside out, but it is no longer necessary to have that knowledge in order

to make the system comply to your requests.

Nowadays you can log in graphically and start all required applications without even

having

to

type

a

single

character,

while

you

still

have

the

ability

to

access

the

core

of the system if needed. Because of its structure, Linux allows a user to grow into

the system: it equally fits new and experienced users. New users are not forced to do

difficult things, while experienced users are not forced to work in the same way they

did when they first started learning Linux.

While

development

in

the

service

area

continues,

great

things

are

being

done

for

desktop

users, generally considered as the group least likely to know how a system works.

Developers of desktop applications are making incredible efforts to make the most

beautiful

desktops

you've

ever

seen,

or

to

make

your

Linux

machine

look

just

like

your

former MS Windows or MacIntosh workstation. The latest developments also include 3D

acceleration support and support for USB devices, single-click updates of system and

packages, and so on. Linux has these, and tries to present all available services in

a logical form that ordinary people can understand.

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1.3. Does Linux have a future?

1.3.1. Open Source

The idea behind Open Source software is rather simple: when programmers can read,

distribute and change code, the code will mature. People can adapt it, fix it, debug

it, and they can do it at a speed that dwarfs the performance of software developers

at

conventional

companies.

This

software

will

be

more

flexible

and

of

a

better

quality

than software that has been developed using the conventional channels, because more

people have tested

it in more

different conditions than the closed

software developer

ever can.

The

Open

Source

initiative

started

to

make

this

clear

to

the

commercial

world,

and

very

slowly, commercial vendors are starting to see the point. While lots of academics and

technical people have already been convinced for 20 years now that this is the way to

go,

commercial

vendors

needed

applications

like

the

Internet

to

make

them

realize

they

can profit from Open Source. Now Linux has grown past the stage where it was almost

exclusively an academic system, useful only to a handful of people with a technical

background. Now Linux provides more than the operating system: there is an entire

infrastructure

supporting

the

chain

of

effort

of

creating

an

operating

system,

of

making

and

testing

programs

for

it,

of

bringing

everything

to

the

users,

of

supplying

maintenance, updates and support and customizations, etcetera. Today, Linux is ready

to accept the challenge of a fast- changing world.

1.3.2. Ten years of experience at your service

While Linux is probably the most well- known Open Source initiative, there is another

project that contributed enormously to the popularity of the Linux operating system.

This project is called SAMBA, and its achievement is the reverse engineering of the

Server

Message

Block

(SMB)/Common

Internet

File

System

(CIFS)

protocol

used

for

file-

and

print- serving

on

PC-related

machines,

natively

supported

by

MS

Windows

NT

and

OS/2,

and

Linux.

Packages

are

now

available

for

almost

every

system

and

provide

interconnection

solutions

in

mixed

environments

using

MS

Windows

protocols:

Windows- compatible (up to and including Win2K) file- and print-servers.

Maybe even more successful than the SAMBA project is the Apache HTTP server project.

The

server

runs

on

UNIX,

Windows

NT

and

many

other

operating

systems.

Originally

known

as

for

the

matured

code

deserves

to

be

connoted

with

the

native

American

tribe

of

the

Apache,

well-known

for

their

superior

skills

in

warfare

strategy

and

inexhaustible

endurance.

Apache has been shown to be substantially faster, more stable and more feature-full

than many other web servers. Apache is run on sites that get millions of visitors per

day, and while no official support is provided by the developers, the Apache user

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community provides answers to all your questions. Commercial support is now being

provided by a number of third parties.

In

the

category

of

office

applications,

a

choice

of

MS

Office

suite

clones

is

available,

ranging

from

partial

to

full

implementations

of

the

applications

available

on

MS

Windows

workstations. These initiatives helped a great deal to make Linux acceptable for the

desktop market, because the users don't need extra training to learn how to work with

new

systems.

With

the

desktop

comes

the

praise

of

the

common

users,

and

not

only

their

praise, but also their specific requirements, which are growing more intricate and

demanding by the day.

The

Open

Source

community,

consisting

largely

of

people

who

have

been

contributing

for

over

half

a

decade,

assures

Linux'

position

as

an

important

player

on

the

desktop

market

as well as in general IT application. Paid employees and volunteers alike are working

diligently so that Linux can maintain a position in the market. The more users, the

more questions. The Open Source community makes

sure answers keep coming, and

watches

the

quality

of

the

answers

with

a

suspicious

eye,

resulting

in

ever

more

stability

and

accessibility.

1.4. Properties of Linux

1.4.1. Linux Pros

A lot of the advantages of Linux are a consequence of Linux' origins, deeply rooted

in UNIX, except for the first advantage, of course:

Linux is free:

As

in

free

beer,

they

say.

If

you

want

to

spend

absolutely

nothing,

you

don't

even

have

to pay the price of a CD. Linux can be downloaded in its entirety from the Internet

completely

for

free.

No

registration

fees,

no

costs

per

user,

free

updates,

and

freely

available source code in case you want to change the behavior of your system.

Most of all, Linux is free as in free speech:

The

license

commonly

used

is

the

GNU

Public

License

(GPL).

The

license

says

that

anybody

who may want to do so, has the right to change Linux and eventually to redistribute

a

changed

version,

on

the

one

condition

that

the

code

is

still

available

after

redistribution. In practice, you are free to grab a kernel image, for instance to add

support

for

teletransportation

machines

or

time

travel

and

sell

your

new

code,

as

long

as your customers can still have a copy of that code.

Linux is portable to any hardware platform:

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A vendor who wants to sell a new type of computer and who doesn't know what kind of

OS his new machine will run (say the CPU in your car or washing machine), can take a

Linux kernel and make it work on his hardware, because documentation related to this

activity is freely available.

Linux was made to keep on running:

As with UNIX, a Linux system expects to run without rebooting all the time. That is

why a lot of tasks are being executed at night or scheduled automatically for other

calm

moments,

resulting

in

higher

availability

during

busier

periods

and

a

more

balanced

use

of

the

hardware.

This

property

allows

for

Linux

to

be

applicable

also

in

environments

where

people

don't

have

the

time

or

the

possibility

to

control

their

systems

night

and

day.

Linux is secure and versatile:

The security model used

in Linux is

based on the UNIX idea of security,

which is known

to

be

robust

and

of

proven

quality.

But

Linux

is

not

only

fit

for

use

as

a

fort

against

enemy

attacks from

the

Internet: it will adapt

equally to

other situations, utilizing

the

same

high

standards

for

security.

Your

development

machine

or

control

station

will

be as secure as your firewall.

Linux is scalable:

From

a

Palmtop

with

2

MB

of

memory

to

a

petabyte

storage

cluster

with

hundreds

of

nodes:

add

or

remove

the

appropriate

packages

and

Linux

fits

all.

You

don't

need

a

supercomputer

anymore,

because

you

can

use

Linux

to

do

big

things

using

the

building

blocks

provided

with the system. If you want to do little things, such as making an operating system

for an embedded processor or just recycling your old 486, Linux will do that as well.

The Linux OS and Linux applications have very short debug-times:

Because Linux has been developed and tested by thousands of people, both errors and

people

to

fix

them

are

found

very

quickly.

It

often

happens

that

there

are

only

a

couple

of hours between discovery and fixing of a bug.

1.4.2. Linux Cons

There are far too many different distributions:

opinions. At first glance, the amount of Linux distributions can be frightening, or

ridiculous,

depending

on

your

point

of

view.

But

it

also

means

that

everyone

will

find

what he or she needs. You don't need to be an expert to find a suitable release.

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