source: clfs-sysroot/BOOK/final-preps/creatingfiles.xml@ f6c417f

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
  "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
  <!ENTITY % general-entities SYSTEM "../general.ent">
  %general-entities;
]>

<sect1 id="ch-final-preps-creatingfiles">
  <?dbhtml filename="creatingfiles.html"?>

  <title>Creating Essential Files</title>

  <para>A proper Linux system maintains a list of the mounted file systems in
  the file <filename>/etc/mtab</filename>.  Normally, this file would be
  created when we mount a new file system. Since we will not be mounting any
  file systems inside our chroot environment, create an empty file for
  utilities that expect the presence of <filename>/etc/mtab</filename>:</para>

<screen><userinput>touch ${LFS}/etc/mtab</userinput></screen>

  <para>In order for user <systemitem class="username">root</systemitem> to be
  able to login and for the name <quote>root</quote> to be recognized, there
  must be relevant entries in the <filename>/etc/passwd</filename> and
  <filename>/etc/group</filename> files.</para>

  <para>Create the <filename>/etc/passwd</filename> file by running the following
  command:</para>

<screen><userinput>cat &gt; ${LFS}/etc/passwd &lt;&lt; "EOF"
<literal>root:x:0:0:root:/root:/bin/bash</literal>
EOF</userinput></screen>

  <para>The actual password for <systemitem class="username">root</systemitem>
  (the <quote>x</quote> used here is just a placeholder) will be set later.</para>

  <para>Create the <filename>/etc/group</filename> file by running the following
  command:</para>

<screen><userinput>cat &gt; ${LFS}/etc/group &lt;&lt; "EOF"
<literal>root:x:0:
bin:x:1:
sys:x:2:
kmem:x:3:
tty:x:4:
tape:x:5:
daemon:x:6:
floppy:x:7:
disk:x:8:
lp:x:9:
dialout:x:10:
audio:x:11:
video:x:12:
utmp:x:13:
usb:x:14:
cdrom:x:15:</literal>
EOF</userinput></screen>

  <para>The created groups are not part of any standard&mdash;they are groups
  decided on in part by the requirements of the Udev configuration in this
  chapter, and in part by common convention employed by a number of existing
  Linux distributions. The Linux Standard Base (LSB, available at <ulink
  url="http://www.linuxbase.org"/>) recommends only that, besides the group
  <systemitem class="groupname">root</systemitem> with a Group ID (GID) of 0,
  a group <systemitem class="groupname">bin</systemitem> with a GID of 1 be
  present. All other group names and GIDs can be chosen freely by the system
  administrator since well-written programs do not depend on GID numbers, but
  rather use the group's name.</para>

  <para>The <command>login</command>, <command>agetty</command>, and
  <command>init</command> programs (and others) use a number of log
  files to record information such as who was logged into the system and
  when. However, these programs will not write to the log files if they
  do not already exist. Initialize the log files and give them
  proper permissions:</para>

<screen><userinput>touch ${LFS}/var/run/utmp ${LFS}/var/log/{btmp,lastlog,wtmp}
chgrp -v utmp ${LFS}/var/run/utmp ${LFS}/var/log/lastlog
chmod -v 664 ${LFS}/var/run/utmp ${LFS}/var/log/lastlog</userinput></screen>

  <para>The <filename>/var/run/utmp</filename> file records the users
  that are currently logged in. The <filename>/var/log/wtmp</filename>
  file records all logins and logouts. The
  <filename>/var/log/lastlog</filename> file records when
  each user last logged in. The <filename>/var/log/btmp</filename> file
  records the bad login attempts.</para>

</sect1>