[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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[b943097] | 42 | <screen><userinput>ln -sv /tools/bin/{bash,cat,echo,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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[e844aee] | 46 | sed 's/tools/usr/' /tools/lib/libstdc++.la > /usr/lib/libstdc++.la
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[5998892] | 47 | ln -sv bash /bin/sh</userinput></screen>
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[673b0d8] | 48 |
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[85e7f3c] | 49 | <para>Historically, Linux maintains a list of the mounted file systems in the
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[ba8848f] | 50 | file <filename>/etc/mtab</filename>. Modern kernels maintain this list
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[85e7f3c] | 51 | internally and exposes it to the user via the <filename
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[ba8848f] | 52 | class="directory">/proc</filename> filesystem. To satisfy utilities that
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[85e7f3c] | 53 | expect the presence of <filename>/etc/mtab</filename>, create the following
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| 54 | symbolic link:</para>
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| 55 |
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| 56 | <screen><userinput>ln -sv /proc/self/mounts /etc/mtab</userinput></screen>
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[d2c332bc] | 57 |
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| 58 | <para>In order for user <systemitem class="username">root</systemitem> to be
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| 59 | able to login and for the name <quote>root</quote> to be recognized, there
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| 60 | must be relevant entries in the <filename>/etc/passwd</filename> and
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| 61 | <filename>/etc/group</filename> files.</para>
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| 62 |
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| 63 | <para>Create the <filename>/etc/passwd</filename> file by running the following
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| 64 | command:</para>
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| 65 |
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| 66 | <screen><userinput>cat > /etc/passwd << "EOF"
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[4361397] | 67 | <literal>root:x:0:0:root:/root:/bin/bash
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[8f90f47d] | 68 | bin:x:1:1:bin:/dev/null:/bin/false
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[390e32c] | 69 | nobody:x:99:99:Unprivileged User:/dev/null:/bin/false</literal>
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[d2c332bc] | 70 | EOF</userinput></screen>
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| 71 |
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| 72 | <para>The actual password for <systemitem class="username">root</systemitem>
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| 73 | (the <quote>x</quote> used here is just a placeholder) will be set later.</para>
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| 74 |
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| 75 | <para>Create the <filename>/etc/group</filename> file by running the following
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| 76 | command:</para>
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| 77 |
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| 78 | <screen><userinput>cat > /etc/group << "EOF"
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| 79 | <literal>root:x:0:
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| 80 | bin:x:1:
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| 81 | sys:x:2:
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| 82 | kmem:x:3:
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[107e7a5] | 83 | tape:x:4:
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| 84 | tty:x:5:
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[d2c332bc] | 85 | daemon:x:6:
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| 86 | floppy:x:7:
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| 87 | disk:x:8:
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| 88 | lp:x:9:
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[bb8939c] | 89 | dialout:x:10:
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[d2c332bc] | 90 | audio:x:11:
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| 91 | video:x:12:
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| 92 | utmp:x:13:
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| 93 | usb:x:14:
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[4361397] | 94 | cdrom:x:15:
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[d1538c0] | 95 | mail:x:34:
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[4361397] | 96 | nogroup:x:99:</literal>
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[d2c332bc] | 97 | EOF</userinput></screen>
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| 98 |
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| 99 | <para>The created groups are not part of any standard—they are groups
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| 100 | decided on in part by the requirements of the Udev configuration in this
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| 101 | chapter, and in part by common convention employed by a number of existing
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| 102 | Linux distributions. The Linux Standard Base (LSB, available at <ulink
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| 103 | url="http://www.linuxbase.org"/>) recommends only that, besides the group
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| 104 | <systemitem class="groupname">root</systemitem> with a Group ID (GID) of 0,
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| 105 | a group <systemitem class="groupname">bin</systemitem> with a GID of 1 be
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| 106 | present. All other group names and GIDs can be chosen freely by the system
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| 107 | administrator since well-written programs do not depend on GID numbers, but
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| 108 | rather use the group's name.</para>
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| 109 |
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| 110 | <para>To remove the <quote>I have no name!</quote> prompt, start a new
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| 111 | shell. Since a full Glibc was installed in <xref
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| 112 | linkend="chapter-temporary-tools"/> and the
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| 113 | <filename>/etc/passwd</filename> and <filename>/etc/group</filename>
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| 114 | files have been created, user name and group name resolution will now
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[f19e766] | 115 | work:</para>
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[d2c332bc] | 116 |
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| 117 | <screen role="nodump"><userinput>exec /tools/bin/bash --login +h</userinput></screen>
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| 118 |
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| 119 | <para>Note the use of the <parameter>+h</parameter> directive. This tells
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| 120 | <command>bash</command> not to use its internal path hashing. Without this
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| 121 | directive, <command>bash</command> would remember the paths to binaries it has
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| 122 | executed. To ensure the use of the newly compiled binaries as soon as they are
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| 123 | installed, the <parameter>+h</parameter> directive will be used for the duration
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| 124 | of this chapter.</para>
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| 125 |
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| 126 | <para>The <command>login</command>, <command>agetty</command>, and
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| 127 | <command>init</command> programs (and others) use a number of log
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| 128 | files to record information such as who was logged into the system and
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| 129 | when. However, these programs will not write to the log files if they
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| 130 | do not already exist. Initialize the log files and give them
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| 131 | proper permissions:</para>
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| 132 |
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[44f6add] | 133 | <screen><userinput>touch /var/log/{btmp,lastlog,wtmp}
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[4f2e707] | 134 | chgrp -v utmp /var/log/lastlog
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| 135 | chmod -v 664 /var/log/lastlog
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| 136 | chmod -v 600 /var/log/btmp</userinput></screen>
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[d2c332bc] | 137 |
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[44f6add] | 138 | <para>The <filename>/var/log/wtmp</filename> file records all logins and
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| 139 | logouts. The <filename>/var/log/lastlog</filename> file records when each
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| 140 | user last logged in. The <filename>/var/log/btmp</filename> file records the
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| 141 | bad login attempts.</para>
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| 142 |
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| 143 | <note><para>The <filename>/run/utmp</filename> file records the users that
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| 144 | are currently logged in. This file is created dynamically in the boot
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| 145 | scripts.</para></note>
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[d2c332bc] | 146 |
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[673b0d8] | 147 | </sect1>
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