| 1 | <sect1 id="ch05-settingenviron">
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| 2 | <title>Setting up the environment</title>
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| 3 | <?dbhtml filename="settingenvironment.html" dir="chapter05"?>
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| 4 |
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| 5 | <para>While logged in as user <emphasis>lfs</emphasis>, issue the
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| 6 | following commands to set up a good work environment:</para>
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| 7 |
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| 8 | <screen><userinput>cat > ~/.bash_profile << "EOF"</userinput>
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| 9 | set +h
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| 10 | umask 022
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| 11 | LFS=/mnt/lfs
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| 12 | LC_ALL=POSIX
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| 13 | PATH=/tools/bin:$PATH
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| 14 | export LFS LC_ALL PATH
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| 15 | unset CC CXX CPP LD_LIBRARY_PATH LD_PRELOAD
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| 16 | <userinput>EOF
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| 17 |
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| 18 | source ~/.bash_profile</userinput></screen>
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| 19 |
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| 20 | <para>The <userinput>set +h</userinput> command turns off
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| 21 | <userinput>bash</userinput>'s hash function. Normally hashing is a useful
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| 22 | feature: <userinput>bash</userinput> uses a hash table to remember the
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| 23 | full pathnames of executable files to avoid searching the PATH time and time
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| 24 | again to find the same executable. However, we'd like the new tools to be
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| 25 | used as soon as they are installed. By switching off the hash function, our
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| 26 | "interactive" commands (<userinput>make</userinput>,
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| 27 | <userinput>patch</userinput>, <userinput>sed</userinput>,
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| 28 | <userinput>cp</userinput> and so forth) will always use
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| 29 | the newest available version during the build process.</para>
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| 30 |
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| 31 | <para>Setting the user file-creation mask to 022 ensures that newly created
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| 32 | files and directories are only writable for their owner, but readable and
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| 33 | executable for anyone.</para>
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| 34 |
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| 35 | <para>The LFS variable should of course be set to the mount point you
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| 36 | chose.</para>
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| 37 |
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| 38 | <para>The LC_ALL variable controls the localization of certain programs,
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| 39 | making their messages follow the conventions of a specified country. If your
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| 40 | host system uses a version of Glibc older than 2.2.4,
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| 41 | having LC_ALL set to something other than "POSIX" or "C" during this chapter
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| 42 | may cause trouble if you exit the chroot environment and wish to return later.
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| 43 | By setting LC_ALL to "POSIX" (or "C", the two are equivalent) we ensure that
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| 44 | everything will work as expected in the chroot environment.</para>
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| 45 |
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| 46 | <para>We prepend <filename>/tools/bin</filename> to the standard PATH so
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| 47 | that, as we move along through this chapter, the tools we build will get used
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| 48 | during the rest of the building process.</para>
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| 49 |
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| 50 | <para>The CC, CXX, CPP, LD_LIBRARY_PATH and LD_PRELOAD environment variables all
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| 51 | have the potential to cause havoc with our Chapter 5 toolchain. We therefore
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| 52 | unset them to prevent any chance of this happening.</para>
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| 53 |
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| 54 | <para>Now, after sourcing the just-created profile, we're all set to begin
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| 55 | building the temporary tools that will support us in later chapters.</para>
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| 56 |
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| 57 | </sect1>
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| 58 |
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