source: chapter06/createfiles.xml@ 46ded2b

7.6-systemd 7.7-systemd 7.7-systemd-rc1 7.8-systemd 7.9-systemd 7.9-systemd-rc1 7.9-systemd-rc2 systemd
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1<?xml version="1.0" encoding="ISO-8859-1"?>
2<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
4 <!ENTITY % general-entities SYSTEM "../general.ent">
5 %general-entities;
6]>
7
8<sect1 id="ch-system-createfiles">
9 <?dbhtml filename="createfiles.html"?>
10
11 <title>Creating Essential Files and Symlinks</title>
12
13 <indexterm zone="ch-system-createfiles">
14 <primary sortas="e-/etc/passwd">/etc/passwd</primary>
15 </indexterm>
16
17 <indexterm zone="ch-system-createfiles">
18 <primary sortas="e-/etc/group">/etc/group</primary>
19 </indexterm>
20
21 <indexterm zone="ch-system-createfiles">
22 <primary sortas="e-/var/run/utmp">/var/run/utmp</primary>
23 </indexterm>
24
25 <indexterm zone="ch-system-createfiles">
26 <primary sortas="e-/var/log/btmp">/var/log/btmp</primary>
27 </indexterm>
28
29 <indexterm zone="ch-system-createfiles">
30 <primary sortas="e-/var/log/lastlog">/var/log/lastlog</primary>
31 </indexterm>
32
33 <indexterm zone="ch-system-createfiles">
34 <primary sortas="e-/var/log/wtmp">/var/log/wtmp</primary>
35 </indexterm>
36
37 <para>Some programs use hard-wired paths to programs which do not exist yet. In
38 order to satisfy these programs, create a number of symbolic links which will be
39 replaced by real files throughout the course of this chapter after the software
40 has been installed:</para>
41
42<screen><userinput>ln -sv /tools/bin/{bash,cat,echo,pwd,stty} /bin
43ln -sv /tools/bin/perl /usr/bin
44ln -sv /tools/lib/libgcc_s.so{,.1} /usr/lib
45ln -sv /tools/lib/libstdc++.so{,.6} /usr/lib
46sed 's/tools/usr/' /tools/lib/libstdc++.la > /usr/lib/libstdc++.la
47ln -sv bash /bin/sh</userinput></screen>
48
49 <variablelist>
50 <title>The purpose of each link:</title>
51
52 <varlistentry>
53 <term><parameter><filename>/bin/bash</filename></parameter></term>
54 <listitem>
55 <para>Many <command>bash</command> scripts specify
56 <filename>/bin/bash</filename>.</para>
57 </listitem>
58 </varlistentry>
59
60 <varlistentry>
61 <term><parameter><filename>/bin/cat</filename></parameter></term>
62 <listitem>
63 <para>This pathname is hard-coded into Glibc's configure script.</para>
64 </listitem>
65 </varlistentry>
66
67 <varlistentry>
68 <term><parameter><filename>/bin/echo</filename></parameter></term>
69 <listitem>
70 <para>This is to satisfy one of the tests in Glibc's test suite, which
71 expects <filename>/bin/echo</filename>.</para>
72 </listitem>
73 </varlistentry>
74
75 <varlistentry>
76 <term><parameter><filename>/bin/pwd</filename></parameter></term>
77 <listitem>
78 <para>Some <command>configure</command> scripts, particularly Glibc's,
79 have this pathname hard-coded.</para>
80 </listitem>
81 </varlistentry>
82
83 <varlistentry>
84 <term><parameter><filename>/bin/stty</filename></parameter></term>
85 <listitem>
86 <para>This pathname is hard-coded into Expect, therefore it is needed
87 for Binutils and GCC test suites to pass.</para>
88 </listitem>
89 </varlistentry>
90
91 <varlistentry>
92 <term><parameter><filename>/usr/bin/perl</filename></parameter></term>
93 <listitem>
94 <para>Many Perl scripts hard-code this path to the
95 <command>perl</command> program.</para>
96 </listitem>
97 </varlistentry>
98
99 <varlistentry>
100 <term><parameter><filename>/usr/lib/libgcc_s.so{,.1}</filename></parameter></term>
101 <listitem>
102 <para>Glibc needs this for the pthreads library to work.</para>
103 </listitem>
104 </varlistentry>
105
106 <varlistentry>
107 <term><parameter><filename>/usr/lib/libstdc++{,.6}</filename></parameter></term>
108 <listitem>
109 <para>This is needed by several tests in Glibc's test suite, as well as
110 for C++ support in GMP.</para>
111 </listitem>
112 </varlistentry>
113
114 <varlistentry>
115 <term><parameter><filename>/usr/lib/libstdc++.la</filename></parameter></term>
116 <listitem>
117 <para>This prevents a <filename class="directory">/tools</filename>
118 reference that would otherwise be in
119 <filename>/usr/lib/libstdc++.la</filename> after GCC is installed.</para>
120 </listitem>
121 </varlistentry>
122
123 <varlistentry>
124 <term><parameter><filename>/bin/sh</filename></parameter></term>
125 <listitem>
126 <para>Many shell scripts hard-code <filename>/bin/sh</filename>.</para>
127 </listitem>
128 </varlistentry>
129
130 </variablelist>
131
132 <para>Historically, Linux maintains a list of the mounted file systems in the
133 file <filename>/etc/mtab</filename>. Modern kernels maintain this list
134 internally and exposes it to the user via the <filename
135 class="directory">/proc</filename> filesystem. To satisfy utilities that
136 expect the presence of <filename>/etc/mtab</filename>, create the following
137 symbolic link:</para>
138
139<screen><userinput>ln -sv /proc/self/mounts /etc/mtab</userinput></screen>
140
141 <para>In order for user <systemitem class="username">root</systemitem> to be
142 able to login and for the name <quote>root</quote> to be recognized, there
143 must be relevant entries in the <filename>/etc/passwd</filename> and
144 <filename>/etc/group</filename> files.</para>
145
146 <para>Create the <filename>/etc/passwd</filename> file by running the following
147 command:</para>
148
149<screen><userinput>cat &gt; /etc/passwd &lt;&lt; "EOF"
150<literal>root:x:0:0:root:/root:/bin/bash
151bin:x:1:1:bin:/dev/null:/bin/false
152daemon:x:6:6:Daemon User:/dev/null:/bin/false
153messagebus:x:18:18:D-Bus Message Daemon User:/var/run/dbus:/bin/false
154systemd-bus-proxy:x:72:72:systemd Bus Proxy:/:/bin/false
155systemd-journal-gateway:x:73:73:systemd Journal Gateway:/:/bin/false
156systemd-journal-remote:x:74:74:systemd Journal Remote:/:/bin/false
157systemd-journal-upload:x:75:75:systemd Journal Upload:/:/bin/false
158systemd-network:x:76:76:systemd Network Management:/:/bin/false
159systemd-resolve:x:77:77:systemd Resolver:/:/bin/false
160systemd-timesync:x:78:78:systemd Time Synchronization:/:/bin/false
161nobody:x:99:99:Unprivileged User:/dev/null:/bin/false</literal>
162EOF</userinput></screen>
163
164 <para>The actual password for <systemitem class="username">root</systemitem>
165 (the <quote>x</quote> used here is just a placeholder) will be set later.</para>
166
167 <para>Create the <filename>/etc/group</filename> file by running the following
168 command:</para>
169
170<screen><userinput>cat &gt; /etc/group &lt;&lt; "EOF"
171<literal>root:x:0:
172bin:x:1:daemon
173sys:x:2:
174kmem:x:3:
175tape:x:4:
176tty:x:5:
177daemon:x:6:
178floppy:x:7:
179disk:x:8:
180lp:x:9:
181dialout:x:10:
182audio:x:11:
183video:x:12:
184utmp:x:13:
185usb:x:14:
186cdrom:x:15:
187adm:x:16:
188messagebus:x:18:
189systemd-journal:x:23:
190input:x:24:
191mail:x:34:
192systemd-bus-proxy:x:72:
193systemd-journal-gateway:x:73:
194systemd-journal-remote:x:74:
195systemd-journal-upload:x:75:
196systemd-network:x:76:
197systemd-resolve:x:77:
198systemd-timesync:x:78:
199nogroup:x:99:
200users:x:999:</literal>
201EOF</userinput></screen>
202
203 <para>The created groups are not part of any standard&mdash;they are groups
204 decided on in part by the requirements of the Udev configuration in this
205 chapter, and in part by common convention employed by a number of existing
206 Linux distributions. In addition, some test suites rely on specific users
207 or groups. The Linux Standard Base (LSB, available at <ulink
208 url="http://www.linuxbase.org"/>) recommends only that, besides the group
209 <systemitem class="groupname">root</systemitem> with a Group ID (GID) of 0,
210 a group <systemitem class="groupname">bin</systemitem> with a GID of 1 be
211 present. All other group names and GIDs can be chosen freely by the system
212 administrator since well-written programs do not depend on GID numbers, but
213 rather use the group's name.</para>
214
215 <para>To remove the <quote>I have no name!</quote> prompt, start a new
216 shell. Since a full Glibc was installed in <xref
217 linkend="chapter-temporary-tools"/> and the
218 <filename>/etc/passwd</filename> and <filename>/etc/group</filename>
219 files have been created, user name and group name resolution will now
220 work:</para>
221
222<screen role="nodump"><userinput>exec /tools/bin/bash --login +h</userinput></screen>
223
224 <para>Note the use of the <parameter>+h</parameter> directive. This tells
225 <command>bash</command> not to use its internal path hashing. Without this
226 directive, <command>bash</command> would remember the paths to binaries it has
227 executed. To ensure the use of the newly compiled binaries as soon as they are
228 installed, the <parameter>+h</parameter> directive will be used for the duration
229 of this chapter.</para>
230
231 <para>The <command>login</command>, <command>agetty</command>, and
232 <command>init</command> programs (and others) use a number of log
233 files to record information such as who was logged into the system and
234 when. However, these programs will not write to the log files if they
235 do not already exist. Initialize the log files and give them
236 proper permissions:</para>
237
238<screen><userinput>touch /var/log/{btmp,lastlog,wtmp}
239chgrp -v utmp /var/log/lastlog
240chmod -v 664 /var/log/lastlog
241chmod -v 600 /var/log/btmp</userinput></screen>
242
243 <para>The <filename>/var/log/wtmp</filename> file records all logins and
244 logouts. The <filename>/var/log/lastlog</filename> file records when each
245 user last logged in. The <filename>/var/log/btmp</filename> file records the
246 bad login attempts.</para>
247
248 <note><para>The <filename>/run/utmp</filename> file records the users that
249 are currently logged in. This file is created dynamically in the boot
250 scripts.</para></note>
251
252</sect1>
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