source: BOOK/chroot/common/chroot.xml@ 1565435

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
  "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
  <!ENTITY % general-entities SYSTEM "../../general.ent">
  %general-entities;
]>

<sect1 id="ch-chroot-chroot">
  <?dbhtml filename="chroot.html"?>

  <title>Entering the Chroot Environment</title>

  <para>It is time to enter the chroot environment to begin building
  and installing the final CLFS system. As user <systemitem
  class="username">root</systemitem>, run the following command to
  enter the realm that is, at the moment, populated with only the
  temporary tools:</para>

<screen><userinput>chroot "${CLFS}" /tools/bin/env -i \
    HOME=/root TERM="${TERM}" PS1='\u:\w\$ ' \
    PATH=/bin:/usr/bin:/sbin:/usr/sbin:/tools/bin \
    /tools/bin/bash --login +h</userinput></screen>

  <para>The <parameter>-i</parameter> option given to the
  <command>env</command> command will clear all variables of the chroot
  environment. After that, only the <envar>HOME</envar>,
  <envar>TERM</envar>, <envar>PS1</envar>, and
  <envar>PATH</envar> variables are set again. The
  <parameter>TERM=${TERM}</parameter> construct will set the
  <envar>TERM</envar> variable inside chroot to the same value as
  outside chroot. This variable is needed for programs like
  <command>vim</command> and <command>less</command> to operate
  properly.  If other variables are needed, such as
  <envar>CFLAGS</envar> or <envar>CXXFLAGS</envar>, this is
  a good place to set them again.</para>

  <para>From this point on, there is no need to use the
  <envar>CLFS</envar> variable anymore, because all work will be
  restricted to the CLFS file system.  This is because the Bash shell is
  told that <filename class="directory">${CLFS}</filename> is now the root
  (<filename class="directory">/</filename>) directory.</para>

  <para>Notice that <filename class="directory">/tools/bin</filename> comes
  last in the <envar>PATH</envar>. This means that a temporary tool will no
  longer be used once its final version is installed. This occurs when the
  shell does not <quote>remember</quote> the locations of executed
  binaries&mdash;for this reason, hashing is switched off by passing the
  <parameter>+h</parameter> option to <command>bash</command>.</para>

  <para>It is important that all the commands throughout the remainder
  of this chapter and the following chapters are run from within the
  chroot environment. If you leave this environment for any reason
  (rebooting for example), remember to first mount the <systemitem
  class="filesystem">proc</systemitem> and <systemitem
  class="filesystem">devpts</systemitem> file systems (discussed in the
  previous section) and enter chroot again before continuing with the
  installations.</para>

  <para>Note that the <command>bash</command> prompt will say
  <computeroutput>I have no name!</computeroutput> This is normal because the
  <filename>/etc/passwd</filename> file has not been created yet.</para>

</sect1>