lfs-book-zh_CN/chapter06/shadowpwd-exp.xml

<sect2>
<title>Command explanations</title>

<para><userinput>sed 's/\(.*\) (nflg || \(.*\))\(.*\)/\1\2\3/' src/useradd.c 
&gt; useradd.c.temp &amp;&amp;</userinput>: This sed is used to fix a 
compilation bug which occurs due to a variable (nflg), being used but not 
defined.</para>

<para><userinput>cp -f limits login.access and others:</userinput> These files
were not installed during the installation of the package so we copy
them manually as those files are used to configure authentication
details on the system.</para>

<para><userinput>sed "s%/var/spool/mail%/var/mail%" login.defs.linux &gt;
/etc/login.defs</userinput>: /var/spool/mail is the old location of the
user mailboxes. The location that is used nowadays is /var/mail.</para>

</sect2>