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4. Linux project
Summary
In 1991, Linus Torvalds made the first
version of his original Linux and released it on the Internet(14).
Linux was the UNIX compatible computer operating system kernel. After
that, many volunteers from around the world joined the Linux project
to improve and debug Linux. Revised versions of Linux were also released
with no charge to anyone who wanted to use it.
The characteristic feature of Linux
development is the introduction and promotion of a new development
style(15) where many volunteers freely and directly join in improving
and debugging the program whenever they want. Torvalds decides which
contribution to accept and to be included in the next revision of
Linux. This style did not produce competing versions of Linux and
kept the uniformity of the operating systems kernel(16),(17). He released
new versions frequently to distribute the results of debugging and
other improvements. This frequent release of new versions made it
possible to manage effectively the willing efforts of volunteers.
This open-style computer software development
resulted in voluntary, enthusiastic, and speedy improvements, and
led to a high performance and high reliability operating system kernel.
Linux development progress
In September 1991, Torvalds released
the first version of Linux0.01. After that,Version 1.00 was released
in 1994, which was the completion of the kernel. Version 2.0, released
in 1996, made Linux a practical operating system(18).
Torvalds plays the central role in Linux
development. The worldwide volunteers develop by themselves a part
of source code that they need and Torvalds decides which source code
revisions to adopt with the help of a filtering process conducted
by his supporting staff. Because of this development process, where
any volunteers develop the programs they need, high quality programs
can be obtained in a short time.
The Linux specification was based on
the UNIX standard specification POSIX. That means that Linux is a
UNIX clone. But the source code of Linux is original and the Linux
source code is freely open for anyone.
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The revision record of Linux is as follows(19),( 20). |
| 1991: |
Torvalds started to develop Linux. Release of Version 0.01. |
| 1994: |
Release of Version 1.00. |
| 1996: |
Release of Version 2.0 for general use and Version 2.1.0 for development use. |
| 1999: |
Release of Version 2.2.0 for general use and Version 2.3.0 for development use. |
| 1999: |
Release of Version 2.2.0 for general use and Version 2.3.0 for development use. |
| 2001: |
Release of Version 2.4.0 for general use. |
From Version 0.01 to 1.00, 119 revisions
were released in 2 years and 5 months. From Version 1.00 to 2.0, 234
revisions were released in 2 years and 3 months. From 2.0 to 2.1.0,
21 revisions were released in 4 months. From 2.1.0 to 2.2.0, 142 revisions
were released in 2 years and 4 months. From 2.2.0 to 2.3.0, 9 revisions
were released in 4 months. From 2.3.0 to 2.4.0, 74 revisions were
released in 1 year and 8 months. In the mostly frequent revision period
in the years from 1994 to 1996, more than 10 revisions were release
per month.
Feature of Linux distribution
The user-friendly package, which contains
installation software, network support software and utility programs
as well as Linux itself, is prepared in CDROM or on a Web site. There
are various types of distribution. Some distributions are provided
at no charge by volunteers. Other distributions are commercially sold
by companies. This distribution system promotes Linux while keeping
the unity of Linux to guarantee compatibility.
In the case of UNIX, the source code
was made available through a for-fee license from AT&T. BSD code,
developed in University of California in Berkeley, can also be obtained
with a license. Using these source codes, each vendor prepared each
commercial package after appropriate revision.
In the UNIX standardization process,
the specification like POSIX was promoted instead of the unification
of the source code itself. The source code of the operating system
kernel was dependent on each vendor. As a result, the source code
was different in each vendor and the specification was different in
its details. The UNIX operating systems cannot be guaranteed to be
compatible with each other.
When some trouble occurs during the
running of an application program, the cause of the trouble cannot
be analyzed because the vendors did not make the source code available.
It is often impossible to determine the reason without the vendor's
cooperation whether the trouble is in the application program or in
the operating systems itself.
Compared with the above-mentioned UNIX
case, in the Linux case, each distribution contains the open source
code, and compatibility with the unified Linux kernel is guaranteed.
Technical support can be provided easily because of the open source
code. The Linux license is provided at no charge. This no-charge license
becomes a great advantage, especially when many machines are used
or a large number of embedded systems are produced.
Worldwide usage of Linux and GNU software
Linux was at first an operating system
for stand-alone desktop computers, and afterwards was improved to
support multiprocessor systems. Linux is widely spreading to be installed
in various kinds of systems; super computers, large-scale systems,
Internet terminals, cellular phones, and other embedded systems. The
programmer who feels that a modification is necessary modifies the
Linux source code. Other people can then use the resulting open source
code.
The Linux share is 25% (1.3 million)
of the worldwide server operating system deliveries in 1999 and 7.8%
of the Japanese server operating systems deliveries in 2000. This
means Linux is the dominant server operating system. Because of their
no-charge for operating systems itself, the market share based on
value of sales is not meaningful. In any case, Linux has produced
a very large market.
GNU software and Linux have begun to
be widely used in server and conventional computer systems, because
of their excellent functionality and reliability and because of the
low systems development cost. Recently, main computer makers have
decided to develop the ability to install Linux in all kinds of their
machines. In May 2001, IBM, Fujitsu, Hitachi and NEC agreed to develop
an operating system for essential business systems such as bank teller
systems, using Linux as a base. Besides the merits of Linux -- low
cost, system stability, high network ability and system compatibility
-- cooperation by these four companies makes it possible to reduce
the development cost and to shorten the development period.
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