1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
|
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
<!ENTITY % general-entities SYSTEM "../general.ent">
%general-entities;
]>
<sect1 id="pre-audience">
<?dbhtml filename="audience.html"?>
<title>Audience</title>
<para>There are many reasons why somebody would want to read this book.
The principal reason is to install a Linux system from the source code.
A question many people raise is, <quote>why go through all the hassle of
manually building a Linux system from scratch when you can just download
and install an existing one?</quote> That is a good question and is the
impetus for this section of the book.</para>
<para>One important reason for LFS's existence is to help people learn
how a Linux system works from the inside out. Building an LFS system
helps demonstrate what makes Linux tick, and how things work together
and depend on each other. One of the best things that this learning
experience provides is the ability to customize Linux to your own tastes
and needs.</para>
<para>A key benefit of LFS is that it allows users to have more control
over the system without relying on someone else's Linux implementation.
With LFS, <emphasis>you</emphasis> are in the driver's seat and dictate
every aspect of the system, such as the directory layout and bootscript
setup. You also dictate where, why, and how programs are installed.</para>
<para>Another benefit of LFS is the ability to create a very compact Linux
system. When installing a regular distribution, one is often forced to
include several programs which are probably never used. These programs
waste disk space, or worse, CPU cycles. It is not difficult to build an
LFS system of less than 100 megabytes (MB), which is substantially smaller
than the majority of existing installations. Does this still sound like a
lot of space? A few of us have been working on creating a very small
embedded LFS system. We successfully built a system that was specialized
to run the Apache web server with approximately 8MB of disk space used.
Further stripping could bring this down to 5 MB or less. Try that with a
regular distribution! This is only one of the many benefits of designing
your own Linux implementation.</para>
<para>We could compare Linux distributions to a hamburger purchased at a
fast-food restaurant—you have no idea what might be in what you are
eating. LFS, on the other hand, does not give you a hamburger. Rather,
LFS provides the recipe to make the exact hamburger desired. This allows
users to review the recipe, omit unwanted ingredients, and add your own
ingredients to enhance the flavor of the burger. When you are satisfied
with the recipe, move on to preparing it. It can be made to exact
specifications—broil it, bake it, deep-fry it, or barbecue it.</para>
<para>Another analogy that we can use is that of comparing LFS with a
finished house. LFS provides the skeletal plan of a house, but it is up
to you to build it. LFS maintains the freedom to adjust plans throughout
the process, customizing it to the user's needs and preferences.</para>
<para>An additional advantage of a custom built Linux system is security.
By compiling the entire system from source code, you are empowered to audit
everything and apply all the security patches desired. It is no longer
necessary to wait for somebody else to compile binary packages that fix a
security hole. Unless you examine the patch and implement it yourself, you
have no guarantee that the new binary package was built correctly and
adequately fixes the problem.</para>
<para>The goal of Linux From Scratch is to build a complete and usable
foundation-level system. Readers who do not wish to build their own Linux
system from scratch may not benefit from the information in this book. If
you only want to know what happens while the computer boots, we recommend
the <quote>From Power Up To Bash Prompt</quote> HOWTO located at
<ulink url="http://axiom.anu.edu.au/~okeefe/p2b/"/> or on The Linux
Documentation Project's (TLDP) website at <ulink
url="http://www.tldp.org/HOWTO/From-PowerUp-To-Bash-Prompt-HOWTO.html"/>.
The HOWTO builds a system which is similar to that of this book, but it
focuses strictly on creating a system capable of booting to a BASH prompt.
Consider your objective. If you wish to build a Linux system while learning
along the way, then this book is your best choice.</para>
<para>There are too many good reasons to build your own LFS system to
list them all here. This section is only the tip of the iceberg. As
you continue in your LFS experience, you will find the power that
information and knowledge truly bring.</para>
</sect1>
|
