[673b0d8] | 1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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[b06ca36] | 2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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| 3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
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[673b0d8] | 4 | <!ENTITY % general-entities SYSTEM "../general.ent">
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| 5 | %general-entities;
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| 6 | ]>
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[8ef8304] | 7 |
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[673b0d8] | 8 | <sect1 id="ch-system-createfiles">
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[8ef8304] | 9 | <?dbhtml filename="createfiles.html"?>
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| 10 |
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[d2c332bc] | 11 | <title>Creating Essential Files and Symlinks</title>
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| 12 |
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| 13 | <indexterm zone="ch-system-createfiles">
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| 14 | <primary sortas="e-/etc/passwd">/etc/passwd</primary>
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| 15 | </indexterm>
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| 16 |
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| 17 | <indexterm zone="ch-system-createfiles">
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| 18 | <primary sortas="e-/etc/group">/etc/group</primary>
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| 19 | </indexterm>
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| 20 |
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| 21 | <indexterm zone="ch-system-createfiles">
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| 22 | <primary sortas="e-/var/run/utmp">/var/run/utmp</primary>
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| 23 | </indexterm>
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| 24 |
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| 25 | <indexterm zone="ch-system-createfiles">
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| 26 | <primary sortas="e-/var/log/btmp">/var/log/btmp</primary>
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| 27 | </indexterm>
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| 28 |
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| 29 | <indexterm zone="ch-system-createfiles">
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| 30 | <primary sortas="e-/var/log/lastlog">/var/log/lastlog</primary>
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| 31 | </indexterm>
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| 32 |
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| 33 | <indexterm zone="ch-system-createfiles">
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| 34 | <primary sortas="e-/var/log/wtmp">/var/log/wtmp</primary>
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| 35 | </indexterm>
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[673b0d8] | 36 |
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[8ef8304] | 37 | <para>Some programs use hard-wired paths to programs which do not exist yet. In
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| 38 | order to satisfy these programs, create a number of symbolic links which will be
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| 39 | replaced by real files throughout the course of this chapter after the software
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[f19e766] | 40 | has been installed:</para>
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[673b0d8] | 41 |
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[5985198] | 42 | <screen><userinput>ln -sv /tools/bin/{bash,cat,echo,grep,pwd,stty} /bin
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[5998892] | 43 | ln -sv /tools/bin/perl /usr/bin
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| 44 | ln -sv /tools/lib/libgcc_s.so{,.1} /usr/lib
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[2f94d109] | 45 | ln -sv /tools/lib/libstdc++.so{,.6} /usr/lib
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[5998892] | 46 | ln -sv bash /bin/sh</userinput></screen>
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[673b0d8] | 47 |
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[d2c332bc] | 48 | <para>A proper Linux system maintains a list of the mounted file systems in
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| 49 | the file <filename>/etc/mtab</filename>. Normally, this file would be
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| 50 | created when we mount a new file system. Since we will not be mounting any
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| 51 | file systems inside our chroot environment, create an empty file for
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| 52 | utilities that expect the presence of <filename>/etc/mtab</filename>:</para>
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| 53 |
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| 54 | <screen><userinput>touch /etc/mtab</userinput></screen>
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| 55 |
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| 56 | <para>In order for user <systemitem class="username">root</systemitem> to be
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| 57 | able to login and for the name <quote>root</quote> to be recognized, there
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| 58 | must be relevant entries in the <filename>/etc/passwd</filename> and
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| 59 | <filename>/etc/group</filename> files.</para>
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| 60 |
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| 61 | <para>Create the <filename>/etc/passwd</filename> file by running the following
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| 62 | command:</para>
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| 63 |
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| 64 | <screen><userinput>cat > /etc/passwd << "EOF"
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[4361397] | 65 | <literal>root:x:0:0:root:/root:/bin/bash
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[390e32c] | 66 | nobody:x:99:99:Unprivileged User:/dev/null:/bin/false</literal>
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[d2c332bc] | 67 | EOF</userinput></screen>
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| 68 |
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| 69 | <para>The actual password for <systemitem class="username">root</systemitem>
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| 70 | (the <quote>x</quote> used here is just a placeholder) will be set later.</para>
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| 71 |
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| 72 | <para>Create the <filename>/etc/group</filename> file by running the following
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| 73 | command:</para>
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| 74 |
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| 75 | <screen><userinput>cat > /etc/group << "EOF"
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| 76 | <literal>root:x:0:
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| 77 | bin:x:1:
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| 78 | sys:x:2:
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| 79 | kmem:x:3:
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| 80 | tty:x:4:
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| 81 | tape:x:5:
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| 82 | daemon:x:6:
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| 83 | floppy:x:7:
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| 84 | disk:x:8:
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| 85 | lp:x:9:
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[8857ace2] | 86 | uucp:x:10:
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[d2c332bc] | 87 | audio:x:11:
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| 88 | video:x:12:
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| 89 | utmp:x:13:
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| 90 | usb:x:14:
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[4361397] | 91 | cdrom:x:15:
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[d1538c0] | 92 | mail:x:34:
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[4361397] | 93 | nogroup:x:99:</literal>
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[d2c332bc] | 94 | EOF</userinput></screen>
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| 95 |
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| 96 | <para>The created groups are not part of any standard—they are groups
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| 97 | decided on in part by the requirements of the Udev configuration in this
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| 98 | chapter, and in part by common convention employed by a number of existing
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| 99 | Linux distributions. The Linux Standard Base (LSB, available at <ulink
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| 100 | url="http://www.linuxbase.org"/>) recommends only that, besides the group
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| 101 | <systemitem class="groupname">root</systemitem> with a Group ID (GID) of 0,
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| 102 | a group <systemitem class="groupname">bin</systemitem> with a GID of 1 be
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| 103 | present. All other group names and GIDs can be chosen freely by the system
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| 104 | administrator since well-written programs do not depend on GID numbers, but
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| 105 | rather use the group's name.</para>
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| 106 |
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| 107 | <para>To remove the <quote>I have no name!</quote> prompt, start a new
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| 108 | shell. Since a full Glibc was installed in <xref
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| 109 | linkend="chapter-temporary-tools"/> and the
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| 110 | <filename>/etc/passwd</filename> and <filename>/etc/group</filename>
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| 111 | files have been created, user name and group name resolution will now
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[f19e766] | 112 | work:</para>
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[d2c332bc] | 113 |
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| 114 | <screen role="nodump"><userinput>exec /tools/bin/bash --login +h</userinput></screen>
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| 115 |
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| 116 | <para>Note the use of the <parameter>+h</parameter> directive. This tells
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| 117 | <command>bash</command> not to use its internal path hashing. Without this
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| 118 | directive, <command>bash</command> would remember the paths to binaries it has
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| 119 | executed. To ensure the use of the newly compiled binaries as soon as they are
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| 120 | installed, the <parameter>+h</parameter> directive will be used for the duration
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| 121 | of this chapter.</para>
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| 122 |
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| 123 | <para>The <command>login</command>, <command>agetty</command>, and
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| 124 | <command>init</command> programs (and others) use a number of log
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| 125 | files to record information such as who was logged into the system and
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| 126 | when. However, these programs will not write to the log files if they
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| 127 | do not already exist. Initialize the log files and give them
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| 128 | proper permissions:</para>
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| 129 |
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| 130 | <screen><userinput>touch /var/run/utmp /var/log/{btmp,lastlog,wtmp}
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| 131 | chgrp -v utmp /var/run/utmp /var/log/lastlog
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| 132 | chmod -v 664 /var/run/utmp /var/log/lastlog</userinput></screen>
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| 133 |
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| 134 | <para>The <filename>/var/run/utmp</filename> file records the users
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| 135 | that are currently logged in. The <filename>/var/log/wtmp</filename>
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| 136 | file records all logins and logouts. The
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| 137 | <filename>/var/log/lastlog</filename> file records when
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| 138 | each user last logged in. The <filename>/var/log/btmp</filename> file
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| 139 | records the bad login attempts.</para>
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| 140 |
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[673b0d8] | 141 | </sect1>
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