Changeset 538aa7a for chapter05/chapter05.xml

Timestamp:

11/20/2003 12:15:47 AM (20 years ago)

Author:

Greg Schafer <greg@…>

Branches:

10.0, 10.0-rc1, 10.1, 10.1-rc1, 11.0, 11.0-rc1, 11.0-rc2, 11.0-rc3, 11.1, 11.1-rc1, 11.2, 11.2-rc1, 11.3, 11.3-rc1, 12.0, 12.0-rc1, 12.1, 12.1-rc1, 6.0, 6.1, 6.1.1, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.5-systemd, 7.6, 7.6-systemd, 7.7, 7.7-systemd, 7.8, 7.8-systemd, 7.9, 7.9-systemd, 8.0, 8.1, 8.2, 8.3, 8.4, 9.0, 9.1, arm, bdubbs/gcc13, ml-11.0, multilib, renodr/libudev-from-systemd, s6-init, trunk, v5_1, v5_1_1, xry111/arm64, xry111/arm64-12.0, xry111/clfs-ng, xry111/lfs-next, xry111/loongarch, xry111/loongarch-12.0, xry111/loongarch-12.1, xry111/mips64el, xry111/pip3, xry111/rust-wip-20221008, xry111/update-glibc

Children:

bcd0ce7

Parents:

5bf7f02

Message:

Chapter 6: - Setting up the environment: Reworked the Bash startup files to enforce a clean environment. Closes Bug 714.

git-svn-id: ​http://svn.linuxfromscratch.org/LFS/trunk/BOOK@3115 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

File:

• chapter05/chapter05.xml (modified) (2 diffs)

chapter05/chapter05.xml

@@ -347 +347 @@
 <?dbhtml filename="settingenvironment.html" dir="chapter05"?>
 
-<para>While logged in as user <emphasis>lfs</emphasis>, issue the
-following commands to set up a good work environment:</para>
+<para>We're going to set up a good working environment by creating two new
+startup files for the Bash shell. While logged in as user
+<emphasis>lfs</emphasis>, issue the following commands to create a new
+<filename>.bash_profile</filename>:</para>
 
 <screen><userinput>cat &gt; ~/.bash_profile &lt;&lt; "EOF"</userinput>
+exec env -i TERM=$TERM /bin/bash
+<userinput>EOF</userinput></screen>
+
+<para>The <userinput>exec env -i TERM=$TERM /bin/bash</userinput> command
+creates a new instance of Bash with a completely empty environment, except for
+the TERM variable. This is needed to ensure that no unwanted and potentially
+hazardous environment variables from the host system leak into our build
+environment. The technique used here is a little non-standard but it achieves
+the goal of enforcing a clean environment. By way of explanation, the initial
+shell is a <emphasis>login</emphasis> shell which reads the
+<filename>.bash_profile</filename>. The new shell instance is a
+<emphasis>non-login</emphasis> shell which reads the
+<filename>.bashrc</filename> (created next).</para>
+
+<para>Now create a new <filename>.bashrc</filename>:</para>
+
+<screen><userinput>cat &gt; ~/.bashrc &lt;&lt; "EOF"</userinput>
 set +h
 umask 022
 LFS=/mnt/lfs
 LC_ALL=POSIX
-PATH=/tools/bin:$PATH
+PATH=/tools/bin:/bin:/usr/bin
 export LFS LC_ALL PATH
-unset CC CXX CPP LD_LIBRARY_PATH LD_PRELOAD
-<userinput>EOF
-
-source ~/.bash_profile</userinput></screen>
+<userinput>EOF</userinput></screen>
 
 <para>The <userinput>set +h</userinput> command turns off
@@ -392 +408 @@
 during the rest of the building process.</para>
 
-<para>The CC, CXX, CPP, LD_LIBRARY_PATH and LD_PRELOAD environment variables all
-have the potential to cause havoc with our Chapter 5 toolchain. We therefore
-unset them to prevent any chance of this happening.</para>
-
-<para>Now, after sourcing the just-created profile, we're all set to begin
+<para>Finally, source the just-created profile so that we're all set to begin
 building the temporary tools that will support us in later chapters.</para>
+
+<screen><userinput>source ~/.bash_profile</userinput></screen>
 
 </sect1>