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<TITLE>Developer.com - Online Reference Library - 0672311739:RED HAT LINUX 2ND EDITION:Introduction to Red Hat Linux and UNIX</TITLE>
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<!-- TITLE=RED HAT LINUX 2ND EDITION //-->
<!-- AUTHOR=DAVID PITTS ET AL //-->
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<A NAME="PAGENUM-1"><P>Page 1</P></A>
<h3><P><a name="1739_ 0">Part I<BR>
</P></h3>
<H2>
Introduction and Installation of Linux
</H2>
<P><B>In This PART
</P></B>
<UL>
<LI> Introduction to Red Hat Linux and UNIX 3
<LI> Installation of Your Red Hat System 11
<LI> LILO 27
</UL>
<A NAME="PAGENUM-2"><P>Page 2</P></A>
<A NAME="PAGENUM-3"><P>Page 3</P></A>
<H3><A NAME="ch01_ 1">
CHAPTER 1
</A></H3>
<H2>
Introduction to Red
Hat Linux and UNIX
</H2>
<B>by David Pitts
</B>
<H3><A NAME="ch01_ 2">
IN THIS CHAPTER
</A></H3>
<UL>
<LI> Advantages of Linux 5
<LI> Copyright and Warranty 7
<LI> Where to Get Red Hat Linux 7
<LI> System Requirements 7
</UL>
<A NAME="PAGENUM-4"><P>Page 4</P></A>
<P>UNIX, not to be confused, as Dilbert's boss once did, with a eunuch, is one of the most
popular operating systems in the world. It is a trademark of The Open Group, but was
originally developed by AT&T. UNIX is a real operating system. A real operating system has, as a
minimum, two qualifications: more than one person can access the computer at the same time
and, while doing so, each person can run multiple applications. This is called being a
multiuser and multitasking operating system. UNIX was originally designed to be such a multitasking
system back in the 1970s, running on mainframes and minicomputers.
</P>
<P>With UNIX, each user logs in using a login name. Optionally (and highly recommended),
the user must also supply a password. The password ensures that the person logging on with
the user login name is really who he or she claims to be. Users don't just log in to any
no-name computer, either. Each computer has a "personality," if you will, which, at a minimum, is
a hostname (mine is Lolly). If the computer is attached to a network, it will have several
other identifying items, including, but not limited to, a domain name and an IP address.
</P>
<P>UNIX will run on just about every platform made. Many vendors purchased the source
code and have developed their own versions. The various vendors (IBM, Hewlett-Packard, Sun,
and so on) have added their own special touches over the years. But they are not the only ones
to further modify UNIX. When UNIX was first developed, the source code was given out
freely to colleges and universities. Two schools, University of California at Berkeley and
Massachusetts Institute of Technology, have been on the front edge of development since the beginning.
</P>
<P>As you can imagine, the UNIX development went haywire. People all over the globe began
to develop tools for UNIX. Unfortunately, there was no coordination to guide all the
development. This caused a lot of differentiation between the different versions of UNIX. Finally, <BR>
standards started to appear. For UNIX, many of the standards fall under the IEEE
POSIX.1 standard.
</P>
<P>The downside of UNIX is that it is big. It is also expensive, especially for a PC version. This
is where Linux comes in. Linux, as explained in a little more detail later in this chapter, was
designed to be small, fast, and inexpensive. So far, the designers have
succeeded.
</P>
<P>Linux was originally created by Linus Torvalds of the University of Helsinki in Finland.
Linus based Linux on a small PC-based implementation of UNIX called
minix. Near the end of 1991, Linux was first made public. In November of that same year version 0.10 was released. A
month later, in December, version 0.11 was released. Linus made the source code freely available
and encouraged others to develop it further. They did. Linux continues to be developed today by
a world-wide team, led by Linus, over the Internet.
</P>
<P>The current stable version of Linux is version 2.0. Linux uses no code from AT&T or any
other proprietary source. Much of the software developed for Linux is developed by the Free
Software Foundation's GNU project. Linux, therefore, is very inexpensive;
as a matter of fact, it is free (but not cheap).
</P>
<A NAME="PAGENUM-5"><P>Page 5</P></A>
<H3><A NAME="ch01_ 3">
Advantages of Linux
</A></H3>
<P>So, why would you choose Linux over UNIX? As already mentioned, Linux is free. Like
UNIX, it is very powerful and is a "real" operating system. Also, it is fairly small compared to
other UNIX operating systems. Many UNIX operating systems require 500MB or more,
whereas Linux can be run on as little as 150MB of space, and it can run on as little as 2MB of
RAM. Realistically, though, you will want to have room for development tools, data, and so on,
which can take up 250MB or more, and your RAM should be 12_16MB (although the more,
the merrier!). Here's what you get in exchange for that valuable space:
</P>
<UL>
<LI> Full multitasking—Multiple tasks can be accomplished and multiple devices can
be accessed at the same time.
<LI> Virtual memory—Linux can use a portion of your hard drive as virtual
memory, which increases the efficiency of your system by keeping active processes in RAM
and placing less frequently used or inactive portions of memory on disk. Virtual
memory also utilizes all your system's memory and doesn't allow memory segmentation
to occur.
<LI> The X Window System—The X Window System is a graphics system for
UNIX machines. This powerful interface supports many applications and is the
standard interface for the industry.
<LI> Built-in networking support—Linux uses standard TCP/IP protocols,
including Network File System (NFS) and Network Information Service (NIS, formerly
known as YP). By connecting your system with an Ethernet card or over a modem to
another system, you can access the Internet.
<LI> Shared libraries—Each
application, instead of keeping its own copy of software,
shares a common library of subroutines that it can call at runtime. This saves a lot of
hard drive space on your system.
<LI> Compatibility with the IEEE POSIX.1 standard—Because of this
compatibility, Linux supports many of the standards set forth for all UNIX systems.
<LI> Nonproprietary source code—The Linux kernel uses no code from AT&T, nor
any other proprietary source. Other organizations, such as commercial companies,
the GNU project, hackers, and programmers from all over the world have
developed software for Linux.
<LI> Lower cost than most other UNIX systems and UNIX clones—If you have
the patience and the time, you can freely download Linux off the Internet. Many
books also come with a free copy. (This book includes it on CD-ROM.)
<LI> GNU software support—Linux can run a wide range of free software
available through the GNU project. This software includes everything from application
development (GNU C and GNU C++) to system administration
(gawk, groff, and so on), to games (for example, GNU Chess, GnuGo, NetHack).
</UL>
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