source: chapter07/chroot.xml@ 9813d3d9

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

  <title>Setting up the Environment</title>

    <para>The current shell is also the <command>init</command> process,
    so exiting from it will cause kernel panic.  Prevent exiting from the
    shell accidentally:</para>

<screen role="nodump"><userinput>enable -n exit
readonly IGNOREEOF=1000</userinput></screen>

    <para>The standard I/O streams of the initial shell process is connected
    with <filename>/dev/console</filename>.  However, the testsuite of some
    packages may expect the standard I/O streams to be connected with a
    <quote>real</quote> TTY device node.  Spawn a new shell process on the
    TTY device with <command>agetty</command>:</para>

<screen role="nodump"><userinput>agetty -n -l /bin/bash <replaceable>tty0</replaceable></userinput></screen>

    <para>If you are working via a serial console, replace
    <replaceable>tty0</replaceable> with the name of the serial console
    device node, for example <literal>ttyS0</literal>.</para>

    <para>The command above spawns a new shell process on the TTY device
    specified in the command, and the initial shell process will run in
    background as an init process with very limited functions. The new shell
    process will output:</para>

<screen role="nodump"><computeroutput>bash: cannot set terminal process group (-1): Inappropriate ioctl for device
bash: no job control in this shell</computeroutput></screen>

    <para>This is normal because the shell is not assigned with a
    controlling terminal yet.  Now set up controlling terminal and
    environment variables:</para>

<screen><userinput>exec setsid -c /usr/bin/env -i  \
    HOME=/root                  \
    TERM="$TERM"                \
    PS1='(lfs) \u:\w\$ '        \
    PATH=/usr/bin:/usr/sbin     \
    /bin/bash --login</userinput></screen>

    <para>The command replace the current shell process with a new shell
    process, with controlling terminal set up.</para>

  <para>The <parameter>-i</parameter> option given to the <command>env</command>
  command will clear all the variables in the 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 to the default value specified by <command>agetty</command>. 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>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>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>

  <para>Now set up a temporary hostname, which is required by test suite of
  some packages:</para>

<screen><userinput>hostname lfs</userinput></screen>

  <note>
    <para>It is important that all the commands throughout the remainder of this
    chapter and the following chapters are run from within the environment
    we've set. 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-kernfsmount"/> and
    <xref linkend="ch-tools-devadjust"/> and set up the environment again before
    continuing with the installation.</para>
  </note>

</sect1>