source: chapter07/chroot.xml

<?xml version="1.0" encoding="UTF-8"?>
<!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-tools-chroot">
  <?dbhtml filename="chroot.html"?>

  <title>Entering the Chroot Environment</title>

  <para>Now that all the packages which are required to build the rest of the
  needed tools are on the system, it is time to enter the chroot environment and
  finish installing the temporary tools. This environment will also be
  used to install the final system. As user <systemitem
  class="username">root</systemitem>, run the following command to enter the
  environment that is, at the moment, populated with nothing but temporary
  tools:</para>

<screen role="nodump"><userinput>chroot "$LFS" /usr/bin/env -i   \
    HOME=/root                  \
    TERM="$TERM"                \
    PS1='(lfs chroot) \u:\w\$ ' \
    PATH=/usr/bin:/usr/sbin     \
    MAKEFLAGS="-j<replaceable>$(nproc)</replaceable>"      \
    TESTSUITEFLAGS="-j<replaceable>$(nproc)</replaceable>" \
    /bin/bash --login</userinput></screen>

  <para>
    If you don't want to use all available logical cores, replace
    <replaceable>$(nproc)</replaceable> with the number of logical cores you
    want to use for building packages in this chapter and the following
    chapters.  The test suites of some packages (notably Autoconf, Libtool,
    and Tar) in &ch-final; are not affected by <envar>MAKEFLAGS</envar>, they
    use a <envar>TESTSUITEFLAGS</envar> environment variable instead. We
    set that here as well for running these test suites with multiple cores.
  </para>

  <para>The <parameter>-i</parameter> option given to the <command>env</command>
  command will clear all the variables in 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 sets the <envar>TERM</envar>
  variable inside chroot to the same value as outside chroot. This variable is
  needed so programs like <command>vim</command> and <command>less</command>
  can operate properly.  If other variables are desired, such as
  <envar>CFLAGS</envar> or <envar>CXXFLAGS</envar>, this is a good place to set
  them.</para>

  <para>From this point on, there is no need to use the
  <envar>LFS</envar> variable any more because all work will be restricted
  to the LFS file system; the <command>chroot</command> command runs the
  Bash shell with the root
  (<filename class="directory">/</filename>) directory set to
  <filename class='directory'>$LFS</filename>.</para>

  <para>Notice that <filename class="directory">/tools/bin</filename> is not
  in the <envar>PATH</envar>. This means that the cross toolchain will no longer be
  used.</para>

  <para>Also 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>

  <note>
    <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), ensure that the virtual kernel filesystems are mounted as
    explained in <xref linkend="ch-tools-bindmount"/> and <xref
    linkend="ch-tools-kernfsmount"/> and enter chroot again before continuing
    with the installation.</para>
  </note>

</sect1>