source: postlfs/config/skel.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
  <!ENTITY % general-entities SYSTEM "../../general.ent">
  %general-entities;
]>

<sect1 id="postlfs-config-skel" xreflabel="Configuring for Adding Users">
  <?dbhtml filename="skel.html"?>


  <title>Configuring for Adding Users</title>

  <indexterm zone="postlfs-config-skel">
    <primary sortas="e-etc-skel">/etc/skel/*</primary>
  </indexterm>

  <indexterm zone="postlfs-config-skel">
    <primary sortas="e-etc-default-useradd">/etc/default/useradd</primary>
  </indexterm>

  <para>
    Together, the <command>/usr/sbin/useradd</command> command and <filename
    class="directory">/etc/skel</filename> directory (both are easy to
    set up and use) provide a way to assure new users are added to your LFS
    system with the same beginning settings for things such as the
    <envar>PATH</envar>, keyboard processing and other environmental variables.
    Using these two facilities makes it easier to assure this initial state for
    each new user added to the system.
  </para>

  <para>
    The <filename class="directory">/etc/skel</filename> directory holds
    copies of various initialization and other files that may be copied to the
    new user's home directory when the <command>/usr/sbin/useradd</command>
    program adds the new user.
  </para>

  <bridgehead renderas="sect5">Useradd</bridgehead>

  <para>
    The <command>useradd</command> program uses a collection of default
    values kept in <filename>/etc/default/useradd</filename>. This file
    is created in a base LFS installation by the
    <application>Shadow</application> package. If it has been removed or
    renamed, the <command>useradd</command> program uses some internal
    defaults.  You can see the default values by running
    <command>/usr/sbin/useradd -D</command>.
  </para>

  <para>
    To change these values, simply modify the
    <filename>/etc/default/useradd</filename> file as the
    <systemitem class='username'>root</systemitem> user. An alternative to
    directly modifying the file is to run <command>useradd</command> as the
    <systemitem class='username'>root</systemitem> user while supplying the
    desired modifications on the command line. Information on how to do this
    can be found in the <command>useradd</command> man page.
  </para>

  <bridgehead renderas="sect5">/etc/skel</bridgehead>

  <para>
    To get started, create an
    <filename class="directory">/etc/skel</filename> directory and make sure it
    is writable only by the system administrator, usually
    <systemitem class="username">root</systemitem>. Creating the directory as
    <systemitem class="username">root</systemitem> is the best way to go.
  </para>

  <para>
    The mode of any files from this part of the book that you put in <filename
    class="directory">/etc/skel</filename> should be writable only by the
    owner. Also, since there is no telling what kind of sensitive information
    a user may eventually place in their copy of these files, you should
    make them unreadable by "group" and "other".
  </para>

  <para>
    You can also put other files in
    <filename class="directory">/etc/skel</filename> and
    different permissions may be needed for them.
  </para>

  <para>
    Decide which initialization files should be provided in every (or most)
    new user's home directory. The decisions you make will affect what you
    do in the next two sections, <xref linkend="postlfs-config-profile"/> and
    <xref linkend="postlfs-config-vimrc"/>. Some or all of those files will be
    useful for <systemitem class="username">root</systemitem>, any
    already-existing users, and new users.
  </para>

  <para>
    The files from those sections that you might want to place in
    <filename class="directory">/etc/skel</filename> include
    <filename>.inputrc</filename>, <filename>.bash_profile</filename>,
    <filename>.bashrc</filename>, <filename>.bash_logout</filename>,
    <filename>.dircolors</filename>, and <filename>.vimrc</filename>. If
    you are unsure which of these should be placed there, just continue to
    the following sections, read each section and any references provided,
    and then make your decision.
  </para>

  <para>
    You will run a slightly modified set of commands for files which are
    placed in <filename class="directory">/etc/skel</filename>. Each section
    will remind you of this. In brief, the book's commands have been written
    for files <emphasis>not</emphasis> added to <filename class="directory">
    /etc/skel</filename> and instead just sends the results to the user's
    home directory. If the file is going to be in <filename class="directory">
    /etc/skel</filename>, change the book's command(s) to send output there
    instead and then just copy the file from <filename class="directory">
    /etc/skel</filename> to the appropriate directories, like <filename
    class="directory">/etc</filename>, <filename class="directory">~
    </filename> or the home directory of any other user already in the system.
  </para>

  <bridgehead renderas="sect5">When Adding a User</bridgehead>

  <para>
    When adding a new user with <command>useradd</command>, use
    the <option>-m</option> parameter, which tells
    <command>useradd</command> to create the user's home directory and
    copy files from <filename class="directory">/etc/skel</filename> (can be
    overridden) to the new user's home directory.  For example (perform as the
    <systemitem class="username">root</systemitem> user):
  </para>

<screen role="root"><userinput>useradd -m <replaceable>&lt;newuser&gt;</replaceable></userinput></screen>

  <para>
    If you are sharing a <filename class="directory">/home</filename>
    or <filename class="directory">/usr/src</filename> with another
    Linux distro (for example, the host distro used for building LFS), you
    can create a user with the same UID (and, same primary group GID) to
    keep the file ownership consistent across the systems.  First, on
    <emphasis>the other distro</emphasis>, get the UID of the user and the
    GID of the user's primary group:
  </para>

<screen role="nodump"><userinput>getent passwd <replaceable>&lt;username&gt;</replaceable> | cut -d ':' -f 3,4</userinput></screen>

  <para>
    The command should output the UID and GID, separated by a colon.  Now
    on the BLFS system, create the primary group and the user:
  </para>

<screen role="root"><userinput>groupadd -g <replaceable>&lt;GID&gt;</replaceable> <replaceable>&lt;username&gt;</replaceable> &amp;&amp;
useradd -u <replaceable>&lt;UID&gt;</replaceable> -g <replaceable>&lt;username&gt;</replaceable> <replaceable>&lt;username&gt;</replaceable></userinput></screen>

</sect1>