source: introduction/important/unpacking.xml@ b92d4b3

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Last change on this file since b92d4b3 was b92d4b3, checked in by Manuel Canales Esparcia <manuel@…>, 18 years ago

Tagged unpacking.xml

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1<?xml version="1.0" encoding="ISO-8859-1"?>
2<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
3 "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
4 <!ENTITY % general-entities SYSTEM "../../general.ent">
5 %general-entities;
6]>
7
8<sect1 id="intro-important-unpacking">
9 <?dbhtml filename="unpacking.html"?>
10
11 <sect1info>
12 <othername>$LastChangedBy$</othername>
13 <date>$Date$</date>
14 </sect1info>
15
16 <title>Notes on Building Software</title>
17
18 <para>Those people who have built an LFS system will be aware
19 of the general principles of downloading and unpacking software. We will
20 however repeat some of that information here for those new to building
21 their own software.</para>
22
23 <para>Each set of installation instructions contains a URL from which you
24 can download the package. We do however keep a selection of patches
25 available via http. These are referenced as needed in the installation
26 instructions.</para>
27
28 <para>While you can keep the source files anywhere you like, we
29 assume that you have unpacked them and unzipped any required patches
30 into <filename>/usr/src</filename>.</para>
31
32 <para>We can not emphasize strongly enough that you should start from a
33 <emphasis>clean source tree</emphasis> each time. This means that if
34 you have had an error, it's usually best to delete the source tree and
35 re-unpack it <emphasis>before</emphasis> trying again. This obviously
36 doesn't apply if you're an advanced user used to hacking Makefiles and C
37 code, but if in doubt, start from a clean tree.</para>
38
39 <sect2>
40 <title>Unpacking the Software</title>
41
42 <para>If a file is tar'ed and compressed, it is unpacked by running one of
43 the following commands:</para>
44
45<screen><command>tar -xvf filename.tar.gz
46tar -xvf filename.tgz
47tar -xvf filename.tar.Z
48tar -xvf filename.tar.bz2</command></screen>
49
50 <para>You can also use a slightly different method:</para>
51
52<screen><command>bzcat filename.tar.bz2 | tar -xv</command></screen>
53
54 <para>Finally, you sometimes need to be able to unpack patches which are
55 generally not tar'ed. The best way to do this is to copy the patch file to
56 <filename>/usr/src</filename> and then to run one of the following commands
57 depending on whether the file is <filename>.gz</filename> or
58 <filename>.bz2</filename>:</para>
59
60<screen><command>gunzip -v patchname.gz
61bunzip2 -v patchname.bz2</command></screen>
62
63 </sect2>
64
65 <sect2>
66 <title>Verifying File Integrity Using 'md5sum'</title>
67
68 <para>Generally, to verify that the downloaded file is genuine and complete,
69 most package maintainers also distribute md5sums of the files.
70 To verify the md5sum of the downloaded files, download both the file and the
71 corresponding md5sum file to the same directory (preferably from different
72 on-line locations), and (assuming file.md5sum is the md5sum file downloaded)
73 run the following command:</para>
74
75<screen><command>md5sum -c file.md5sum</command></screen>
76
77 <para>If there are any errors, they will be reported.</para>
78
79 </sect2>
80
81 <sect2>
82 <title>Creating Log Files During Installation</title>
83
84 <para>For larger packages, it is convenient to create log files instead of
85 staring at the screen hoping to catch a particular error or warning. Log files
86 are also useful for debugging and keeping records. The following command
87 allows you to create an installation log. Replace &lt;command&gt; with the
88 command you intend to execute.</para>
89
90<screen><command>( &lt;command&gt; 2&gt;&amp;1 | tee compile.log &amp;&amp; exit $PIPESTATUS )</command></screen>
91
92 <para><option>2&gt;&amp;1</option> redirects error messages to the same
93 location as standard output. The <command>tee</command> command allows
94 viewing of the output while logging the results to a file. The parentheses
95 around the command run the entire command in a subshell and finally the
96 <command>exit $PIPESTATUS</command> ensures the result of the
97 &lt;command&gt; is returned as the result and not the result of the
98 <command>tee</command> command.</para>
99
100 </sect2>
101
102</sect1>
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