| 1 | <sect1 id="ch06-chroot">
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| 2 | <title>Entering the chroot environment</title>
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| 3 | <?dbhtml filename="chroot.html" dir="chapter06"?>
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| 4 |
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| 5 | <para>It is time to enter the chroot environment in order to begin installing
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| 6 | the packages we need. Before you can chroot, however, you need to become
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| 7 | <emphasis>root</emphasis>, since only <emphasis>root</emphasis>
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| 8 | can execute the <userinput>chroot</userinput> command.</para>
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| 9 |
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| 10 | <para>Just like earlier, ensure the LFS environment variable is set up properly
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| 11 | by running <userinput>echo $LFS</userinput> and ensuring it shows the path to
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| 12 | your LFS partition's mount point, which is
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| 13 | <filename class="directory">/mnt/lfs</filename> if you followed our
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| 14 | example.</para>
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| 15 |
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| 16 | <para>Become <emphasis>root</emphasis> and run the following command
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| 17 | to enter the chroot environment:</para>
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| 18 |
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| 19 | <para><screen><userinput>chroot $LFS /tools/bin/env -i \
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| 20 | HOME=/root TERM=$TERM PS1='\u:\w\$ ' \
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| 21 | PATH=/bin:/usr/bin:/sbin:/usr/sbin:/tools/bin \
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| 22 | /tools/bin/bash --login</userinput></screen>
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| 23 | </para>
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| 24 |
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| 25 | <para><screen><userinput>set +h</userinput></screen></para>
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| 26 |
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| 27 | <para>The <userinput>-i</userinput> option given to the
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| 28 | <userinput>env</userinput> command will clear all variables of the chroot
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| 29 | environment. After that, only the HOME, TERM, PS1 and PATH variables are
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| 30 | set again. The TERM=$TERM construct will set the TERM variable inside chroot
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| 31 | to the same value as outside chroot; this variable is needed for programs
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| 32 | like vim and less to operate properly. If you need other variables present,
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| 33 | such as CFLAGS or CXXFLAGS, this is a good place to set them again.</para>
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| 34 |
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| 35 | <para>Also note the use of the set +h directive. This tells bash to not use
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| 36 | its internal path hashing. Without this directive, bash will remember paths
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| 37 | to binaries. Since as we go thru chapter 6, we want to use our newly compiled
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| 38 | binaries as soon as they are installed, we turn off this function.</para>
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| 39 |
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| 40 | <para>From this point on there's no need to use the LFS variable anymore,
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| 41 | because everything you do will be restricted to the LFS file system -- since
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| 42 | what the shell thinks is <filename class="directory">/</filename> is actually
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| 43 | the value of <filename class="directory">$LFS</filename>, which was passed to
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| 44 | the chroot command.</para>
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| 45 |
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| 46 | <para>You have to make sure all the commands in the rest of this chapter and
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| 47 | in the following chapters are run from within the chroot environment.
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| 48 | If you ever leave this environment for any reason (rebooting for example),
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| 49 | you must remember to again enter chroot and mount the proc and devpts
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| 50 | filesystems (discussed later) before continuing with the installations.</para>
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| 51 |
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| 52 | <para>Note that the bash prompt will say "I have no name!" This is
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| 53 | normal, as the <filename>/etc/passwd</filename> file has not been
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| 54 | created yet.</para>
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| 55 |
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| 56 | </sect1>
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| 57 |
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