lfs-book-zh_CN/chapter04/aboutlfs.xml

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<sect1 id="prepare-aboutlfs">
<title>About $LFS</title>
<?dbhtml filename="aboutlfs.html"?>

<para>Throughout this book, the environment variable <envar>LFS</envar> will
be used several times. It is paramount that this variable is always defined.
It should be set to the mount point chosen for the LFS partition.
Check that the <envar>LFS</envar> variable is set up properly with:</para>

<screen role="nodump"><userinput>echo $LFS</userinput></screen>

<para>Make sure the output shows the path to the LFS partition's mount
point, which is <filename class="directory">/mnt/lfs</filename> if the
provided example was followed. If the output is incorrect, the
variable can be set with:</para>

<screen role="nodump"><userinput>export LFS=/mnt/lfs</userinput></screen>

<para>Having this variable set is beneficial in that commands such as
<command>mkdir $LFS/tools</command> can be typed literally. The shell
will automatically replace <quote>$LFS</quote> with
<quote>/mnt/lfs</quote> (or whatever the variable was set to) when it
processes the command line.</para>

<para>Do not forget to check that <envar>$LFS</envar> is set whenever
you leave and reenter the current working environment (as when doing a
<quote>su</quote> to <emphasis>root</emphasis> or another user).</para>

</sect1>