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

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git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@3115 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689
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Greg Schafer 2003-11-20 00:15:47 +00:00
parent 5bf7f02e3f
commit 538aa7a11c
3 changed files with 31 additions and 14 deletions
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3
chapter01/changelog.xml
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@ -35,6 +35,9 @@
</itemizedlist>
</listitem>
<listitem><para>November 19th, 2003 [greg]: Chapter 6: - Setting up the
environment: Reworked the Bash startup files to enforce a clean environment.
Closes Bug 714.</para></listitem>
<listitem><para>November 17th, 2003 [jeremy]: Upgraded Man-Pages to 1.63</para></listitem>

38
chapter05/chapter05.xml
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@ -346,20 +346,36 @@ start a new, clean shell.</para>
<title>Setting up the environment</title>
<?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
<userinput>bash</userinput>'s hash function. Normally hashing is a useful
@ -391,13 +407,11 @@ everything will work as expected in the chroot environment.</para>
that, as we move along through this chapter, the tools we build will get used
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>

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index.xml
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@ -3,8 +3,8 @@
"/usr/share/docbook/docbookx.dtd" [
<!ENTITY version "CVS-20031117">
<!ENTITY releasedate "November 17th, 2003">
<!ENTITY version "CVS-20031119">
<!ENTITY releasedate "November 19th, 2003">
<!ENTITY milestone "5.1">
<!ENTITY nbsp " ">