File: useradd.8.xml

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<?xml version="1.0" encoding="UTF-8"?>
<!--
   Copyright (c) 1991 - 1994, Julianne Frances Haugh
   Copyright (c) 2007 - 2011, Nicolas François
   All rights reserved.
  
   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions
   are met:
   1. Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
   2. Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
   3. The name of the copyright holders or contributors may not be used to
      endorse or promote products derived from this software without
      specific prior written permission.
  
   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
   PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT
   HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook V4.5//EN"
  "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
<!ENTITY CREATE_HOME           SYSTEM "login.defs.d/CREATE_HOME.xml">
<!ENTITY GID_MAX               SYSTEM "login.defs.d/GID_MAX.xml">
<!ENTITY MAIL_DIR              SYSTEM "login.defs.d/MAIL_DIR.xml">
<!ENTITY MAX_MEMBERS_PER_GROUP SYSTEM "login.defs.d/MAX_MEMBERS_PER_GROUP.xml">
<!ENTITY PASS_MAX_DAYS         SYSTEM "login.defs.d/PASS_MAX_DAYS.xml">
<!ENTITY PASS_MIN_DAYS         SYSTEM "login.defs.d/PASS_MIN_DAYS.xml">
<!ENTITY PASS_WARN_AGE         SYSTEM "login.defs.d/PASS_WARN_AGE.xml">
<!ENTITY SUB_GID_COUNT         SYSTEM "login.defs.d/SUB_GID_COUNT.xml">
<!ENTITY SUB_UID_COUNT         SYSTEM "login.defs.d/SUB_UID_COUNT.xml">
<!ENTITY SYS_GID_MAX           SYSTEM "login.defs.d/SYS_GID_MAX.xml">
<!ENTITY SYS_UID_MAX           SYSTEM "login.defs.d/SYS_UID_MAX.xml">
<!ENTITY UID_MAX               SYSTEM "login.defs.d/UID_MAX.xml">
<!ENTITY UMASK                 SYSTEM "login.defs.d/UMASK.xml">
<!ENTITY TCB_AUTH_GROUP        SYSTEM "login.defs.d/TCB_AUTH_GROUP.xml">
<!ENTITY TCB_SYMLINKS          SYSTEM "login.defs.d/TCB_SYMLINKS.xml">
<!ENTITY USE_TCB               SYSTEM "login.defs.d/USE_TCB.xml">
<!ENTITY USERGROUPS_ENAB       SYSTEM "login.defs.d/USERGROUPS_ENAB.xml">
<!-- SHADOW-CONFIG-HERE -->
]>
<refentry id='useradd.8'>
  <!--  $Id$ -->
  <refentryinfo>
    <author>
      <firstname>Julianne Frances</firstname>
      <surname>Haugh</surname>
      <contrib>Creation, 1991</contrib>
    </author>
    <author>
      <firstname>Thomas</firstname>
      <surname>Kłoczko</surname>
      <email>kloczek@pld.org.pl</email>
      <contrib>shadow-utils maintainer, 2000 - 2007</contrib>
    </author>
    <author>
      <firstname>Nicolas</firstname>
      <surname>François</surname>
      <email>nicolas.francois@centraliens.net</email>
      <contrib>shadow-utils maintainer, 2007 - now</contrib>
    </author>
  </refentryinfo>
  <refmeta>
    <refentrytitle>useradd</refentrytitle>
    <manvolnum>8</manvolnum>
    <refmiscinfo class="sectdesc">System Management Commands</refmiscinfo>
    <refmiscinfo class="source">shadow-utils</refmiscinfo>
    <refmiscinfo class="version">&SHADOW_UTILS_VERSION;</refmiscinfo>
  </refmeta>
  <refnamediv id='name'>
    <refname>useradd</refname>
    <refpurpose>create a new user or update default new user information</refpurpose>
  </refnamediv>
  <refsynopsisdiv id='synopsis'>
    <cmdsynopsis>
      <command>useradd</command>
      <arg choice='opt'>
	<replaceable>options</replaceable>
      </arg>
      <arg choice='plain'><replaceable>LOGIN</replaceable></arg>
    </cmdsynopsis>
    <cmdsynopsis>
      <command>useradd</command>
      <arg choice='plain'>-D </arg>
    </cmdsynopsis>
    <cmdsynopsis>
      <command>useradd</command>
      <arg choice='plain'>-D </arg>
      <arg choice='opt'>
	<replaceable>options</replaceable>
      </arg>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1 id='description'>
    <title>DESCRIPTION</title>
      <para>
	<command>useradd</command> is a low level utility for adding
	users.  On Debian, administrators should usually use
	<citerefentry><refentrytitle>adduser</refentrytitle>
	<manvolnum>8</manvolnum></citerefentry> instead.
      </para>
      <para>
	When invoked without the <option>-D</option> option, the
	<command>useradd</command> command creates a new user account using
	the values specified on the command line plus the default values from
	the system. Depending on command line options, the
	<command>useradd</command> command
	will update system files and may also create the new user's home
	directory and copy initial files.
      </para>
      <para>
	By default, a group will also be created for the new user (see
	<option>-g</option>, <option>-N</option>, <option>-U</option>, and
	<option>USERGROUPS_ENAB</option>).
      </para>
  </refsect1>

  <refsect1 id='options'>
    <title>OPTIONS</title>
    <para>The options which apply to the <command>useradd</command> command are:
    </para>
    <variablelist remap='IP'>
      <varlistentry>
	<term>
	  <option>-b</option>, <option>--base-dir</option>&nbsp;<replaceable>BASE_DIR</replaceable>
	</term>
	<listitem>
	  <para>
	    The default base directory for the system if <option>-d</option>&nbsp;<replaceable>HOME_DIR</replaceable> is not specified.
	    <replaceable>BASE_DIR</replaceable> is
	    concatenated with the account name to define the home directory. 
	    If the <option>-m</option> option is not used,
	    <replaceable>BASE_DIR</replaceable> must exist.
	  </para>
	  <para>
	    If this option is not specified, <command>useradd</command>
	    will use the base directory specified by the
	    <option>HOME</option> variable in
	    <filename>/etc/default/useradd</filename>, or
	    <filename>/home</filename> by default.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>
	  <option>-c</option>, <option>--comment</option>&nbsp;<replaceable>COMMENT</replaceable>
	</term>
	<listitem>
	  <para>
	    Any text string. It is generally a short description of the
	    login, and is currently used as the field for the user's full
	    name.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>
	  <option>-d</option>, <option>--home-dir</option>&nbsp;<replaceable>HOME_DIR</replaceable>
	</term>
	<listitem>
	  <para>
	    The new user will be created using
	    <replaceable>HOME_DIR</replaceable> as the value for the user's
	    login directory. The default is to append the
	    <replaceable>LOGIN</replaceable> name to
	    <replaceable>BASE_DIR</replaceable> and use that as the login
	    directory name. The directory <replaceable>HOME_DIR</replaceable>
	    does not have to exist but will not be created if it is missing.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>
	  <option>-D</option>, <option>--defaults</option>
	</term>
	<listitem>
	  <para>
	    See below, the subsection "Changing the default values".
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>
	  <option>-e</option>, <option>--expiredate</option>&nbsp;<replaceable>EXPIRE_DATE</replaceable>
	</term>
	<listitem>
	  <para>
	    The date on which the user account will be disabled. The date is
	    specified in the format <emphasis remap='I'>YYYY-MM-DD</emphasis>.
	  </para>
	  <para>
	    If not specified, <command>useradd</command> will use the
	    default expiry date specified by the <option>EXPIRE</option>
	    variable in <filename>/etc/default/useradd</filename>, or
	    an empty string (no expiry) by default.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>
	  <option>-f</option>, <option>--inactive</option>&nbsp;<replaceable>INACTIVE</replaceable>
	</term>
	<listitem>
	  <para>
	    The number of days after a password expires until the account is
	    permanently disabled. A value of 0 disables the account as soon
	    as the password has expired, and a value of -1 disables the
	    feature.
	  </para>
	  <para>
	    If not specified, <command>useradd</command> will use the
	    default inactivity period specified by the
	    <option>INACTIVE</option> variable in
	    <filename>/etc/default/useradd</filename>, or -1 by default.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>
	  <option>-g</option>, <option>--gid</option>&nbsp;<replaceable>GROUP</replaceable>
	</term>
	<listitem>
	  <para>
	    The group name or number of the user's initial login group. The
	    group name must exist. A group number must refer to an already
	    existing group.
	  </para>
	  <para>
	    If not specified, the behavior of <command>useradd</command>
	    will depend on the <option>USERGROUPS_ENAB</option> variable
	    in <filename>/etc/login.defs</filename>. If this variable is
	    set to <replaceable>yes</replaceable> (or
	    <option>-U/--user-group</option> is specified on the command
	    line), a group will be created for the user, with the same
	    name as her loginname. If the variable is set to
	    <replaceable>no</replaceable> (or
	    <option>-N/--no-user-group</option> is specified on the
	    command line), useradd will set the primary group of the new
	    user to the value specified by the <option>GROUP</option>
	    variable in <filename>/etc/default/useradd</filename>, or
	    100 by default.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>
	  <option>-G</option>, <option>--groups</option>&nbsp;<replaceable>GROUP1</replaceable>[<emphasis remap='I'>,GROUP2,...</emphasis>[<emphasis remap='I'>,GROUPN</emphasis>]]]
	</term>
	<listitem>
	  <para>
	    A list of supplementary groups which the user is also a member
	    of. Each group is separated from the next by a comma, with no
	    intervening whitespace. The groups are subject to the same
	    restrictions as the group given with the <option>-g</option>
	    option. The default is for the user to belong only to the
	    initial group.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><option>-h</option>, <option>--help</option></term>
	<listitem>
	  <para>Display help message and exit.</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>
	  <option>-k</option>, <option>--skel</option>&nbsp;<replaceable>SKEL_DIR</replaceable>
	</term>
	<listitem>
	  <para>
	    The skeleton directory, which contains files and directories
	    to be copied in the user's home directory, when the home
	    directory is created by <command>useradd</command>.
	  </para>
	  <para>
	    This option is only valid if the <option>-m</option> (or
	    <option>--create-home</option>) option is specified.
	  </para>
	  <para>
	    If this option is not set, the skeleton directory is defined
	    by the <option>SKEL</option> variable in
	    <filename>/etc/default/useradd</filename> or, by default,
	    <filename>/etc/skel</filename>.
	  </para>
	  <para>
	    If possible, the ACLs and extended attributes are copied.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>
	  <option>-K</option>, <option>--key</option>&nbsp;<replaceable>KEY</replaceable>=<replaceable>VALUE</replaceable>
	</term>
	<listitem>
	  <para>
	    Overrides <filename>/etc/login.defs</filename> defaults
	    (<option>UID_MIN</option>, <option>UID_MAX</option>,
	    <option>UMASK</option>, <option>PASS_MAX_DAYS</option>
	    and others).
	  <para>
	  </para>
	    Example: <option>-K</option>&nbsp;<replaceable>PASS_MAX_DAYS</replaceable>=<replaceable>-1</replaceable>
	    can be used when creating system account to turn off password
	    ageing, even though system account has no password at all.
	    Multiple <option>-K</option> options can be specified, e.g.:
	    <option>-K</option>&nbsp;<replaceable>UID_MIN</replaceable>=<replaceable>100</replaceable>&nbsp;
	    <option>-K</option>&nbsp;<replaceable>UID_MAX</replaceable>=<replaceable>499</replaceable>
	  </para>
	  <!--para>
	    Note: <option>-K</option>&nbsp;<replaceable>UID_MIN</replaceable>=<replaceable>10</replaceable>,<replaceable>UID_MAX</replaceable>=<replaceable>499</replaceable>
	    doesn't work yet.
	  </para-->
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><option>-l</option>, <option>--no-log-init</option></term>
	<listitem>
	  <para>
	    Do not add the user to the lastlog and faillog databases.
	  </para>
	  <para>
	    By default, the user's entries in the lastlog and faillog
	    databases are resetted to avoid reusing the entry from a previously
	    deleted user.
	  </para>
          <para>
            For the compatibility with previous Debian's
            <command>useradd</command>, the <option>-O</option> option is
            also supported.
          </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>
	  <option>-m</option>, <option>--create-home</option>
	</term>
	<listitem>
	  <para>
	    Create the user's home directory if it does not exist. 
	    The files and directories contained in the skeleton directory
	    (which can be defined with the <option>-k</option> option)
	    will be copied to the home directory.
	  </para>
	  <para>
	    By default, if this option is not specified and
	    <option>CREATE_HOME</option> is not enabled, no home
	    directories are created.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>
	  <option>-M</option>
	</term>
	<listitem>
	  <para>
	    Do no create the user's home directory, even if the system
	    wide setting from <filename>/etc/login.defs</filename>
	    (<option>CREATE_HOME</option>) is set to
	    <replaceable>yes</replaceable>.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>
	  <option>-N</option>, <option>--no-user-group</option>
	</term>
	<listitem>
	  <para>
	    Do not create a group with the same name as the user, but
	    add the user to the group specified by the <option>-g</option>
	    option or by the <option>GROUP</option> variable in
	    <filename>/etc/default/useradd</filename>.
	  </para>
	  <para>
	    The default behavior (if the <option>-g</option>,
	    <option>-N</option>, and <option>-U</option> options are not
	    specified) is defined by the <option>USERGROUPS_ENAB</option>
	    variable in <filename>/etc/login.defs</filename>.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>
	  <option>-o</option>, <option>--non-unique</option>
	</term>
	<listitem>
	  <para>Allow the creation of a user account with a duplicate (non-unique) UID.</para>
	  <para>
	    This option is only valid in combination with the
	    <option>-u</option> option.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>
	  <option>-p</option>, <option>--password</option>&nbsp;<replaceable>PASSWORD</replaceable>
	</term>
	<listitem>
	  <para>
	    The encrypted password, as returned by <citerefentry>
	    <refentrytitle>crypt</refentrytitle><manvolnum>3</manvolnum>
	    </citerefentry>. The default is to disable the password.
	  </para>
	  <para>
	    <emphasis role="bold">Note:</emphasis> This option is not
	    recommended because the password (or encrypted password) will
	    be visible by users listing the processes.
	  </para>
	  <para>
	    You should make sure the password respects the system's
	    password policy.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>
	  <option>-r</option>, <option>--system</option>
	</term>
	<listitem>
	  <para>
	    Create a system account.
	  </para>
	  <para>
	    System users will be created with no aging information in
	    <filename>/etc/shadow</filename>, and their numeric
	    identifiers are chosen in the
	    <option>SYS_UID_MIN</option>-<option>SYS_UID_MAX</option>
	    range, defined in <filename>/etc/login.defs</filename>, instead of
	    <option>UID_MIN</option>-<option>UID_MAX</option> (and their
	    <option>GID</option> counterparts for the creation of groups).
	  </para>
	  <para>
	    Note that <command>useradd</command> will not create a home
	    directory for such an user, regardless of the default setting
	    in <filename>/etc/login.defs</filename>
	    (<option>CREATE_HOME</option>). You have to specify the
	    <option>-m</option> options if you want a home directory for a
	    system account to be created.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>
	  <option>-R</option>, <option>--root</option>&nbsp;<replaceable>CHROOT_DIR</replaceable>
	</term>
	<listitem>
	  <para>
	    Apply changes in the <replaceable>CHROOT_DIR</replaceable>
	    directory and use the configuration files from the
	    <replaceable>CHROOT_DIR</replaceable> directory.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>
	  <option>-s</option>, <option>--shell</option>&nbsp;<replaceable>SHELL</replaceable>
	</term>
	<listitem>
	  <para>
	    The name of the user's login shell. The default is to leave this
	    field blank, which causes the system to select the default login
	    shell specified by the <option>SHELL</option> variable in
	    <filename>/etc/default/useradd</filename>, or an empty string
	    by default.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>
	  <option>-u</option>, <option>--uid</option>&nbsp;<replaceable>UID</replaceable>
	</term>
	<listitem>
	  <para>
	    The numerical value of the user's ID. This value must be unique,
	    unless the <option>-o</option> option is used. The value must be
	    non-negative. The default is to use the smallest ID value
	    greater than or equal to <option>UID_MIN</option> and greater
	    than every other user.
	  </para>
	  <para>
	    See also the <option>-r</option> option and the
	    <option>UID_MAX</option> description.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>
	  <option>-U</option>, <option>--user-group</option>
	</term>
	<listitem>
	  <para>
	    Create a group with the same name as the user, and
	    add the user to this group.
	  </para>
	  <para>
	    The default behavior (if the <option>-g</option>,
	    <option>-N</option>, and <option>-U</option> options are not
	    specified) is defined by the <option>USERGROUPS_ENAB</option>
	    variable in <filename>/etc/login.defs</filename>.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>
	  <option>-Z</option>, <option>--selinux-user</option>&nbsp;<replaceable>SEUSER</replaceable>
	</term>
	<listitem>
	  <para>
	    The SELinux user for the user's login. The default is to leave this
	    field blank, which causes the system to select the default SELinux
	    user.
	  </para>
	</listitem>
      </varlistentry>
    </variablelist>

    <refsect2 id='changing_the_default_values'>
      <title>Changing the default values</title>
      <para>
	When invoked with only the <option>-D</option> option,
	<command>useradd</command> will display the current default values.
	When invoked with <option>-D</option> plus other options,
	<command>useradd</command> will update the default values for the
	specified options. Valid default-changing options are:
      </para>
      <variablelist remap='IP'>
	<varlistentry>
	  <term>
	    <option>-b</option>, <option>--base-dir</option>&nbsp;<replaceable>BASE_DIR</replaceable>
	  </term>
	  <listitem>
	    <para>
	      The path prefix for a new user's home directory. The
	      user's name will be affixed to the end of
	      <replaceable>BASE_DIR</replaceable> to form the new user's
	      home directory name, if the <option>-d</option> option is not used
	      when creating a new account.
	    </para>
	    <para>
	      This option sets the <option>HOME</option> variable in
	      <filename>/etc/default/useradd</filename>.
	    </para>
	  </listitem>
	</varlistentry>
	<varlistentry>
	  <term>
	    <option>-e</option>, <option>--expiredate</option>&nbsp;<replaceable>EXPIRE_DATE</replaceable>
	  </term>
	  <listitem>
	    <para>The date on which the user account is disabled.</para>
	    <para>
	      This option sets the <option>EXPIRE</option> variable in
	      <filename>/etc/default/useradd</filename>.
	    </para>
	  </listitem>
	</varlistentry>
	<varlistentry>
	  <term>
	    <option>-f</option>, <option>--inactive</option>&nbsp;<replaceable>INACTIVE</replaceable>
	  </term>
	  <listitem>
	    <para>
	      The number of days after a password has expired before the
	      account will be disabled.
	    </para>
	    <para>
	      This option sets the <option>INACTIVE</option> variable in
	      <filename>/etc/default/useradd</filename>.
	    </para>
	  </listitem>
	</varlistentry>
	<varlistentry>
	  <term>
	    <option>-g</option>, <option>--gid</option>&nbsp;<replaceable>GROUP</replaceable>
	  </term>
	  <listitem>
	    <para>
	      The group name or ID for a new user's initial group (when
	      the <option>-N/--no-user-group</option> is used or when the
	      <option>USERGROUPS_ENAB</option> variable is set to
	      <replaceable>no</replaceable> in
	      <filename>/etc/login.defs</filename>). The named
	      group must exist, and a numerical group ID must have an
	      existing entry.
	    </para>
	    <para>
	      This option sets the <option>GROUP</option> variable in
	      <filename>/etc/default/useradd</filename>.
	    </para>
	  </listitem>
	</varlistentry>
	<varlistentry>
	  <term>
	    <option>-s</option>, <option>--shell</option>&nbsp;<replaceable>SHELL</replaceable>
	  </term>
	  <listitem>
	    <para>
	      The name of a new user's login shell.
	    </para>
	    <para>
	      This option sets the <option>SHELL</option> variable in
	      <filename>/etc/default/useradd</filename>.
	    </para>
	  </listitem>
	</varlistentry>
      </variablelist>

    </refsect2>
  </refsect1>

  <refsect1 id='notes'>
    <title>NOTES</title>
    <para>The system administrator is responsible for placing the default
      user files in the <filename>/etc/skel/</filename> directory (or any
      other skeleton directory specified in
      <filename>/etc/default/useradd</filename> or on the command line).
    </para>
  </refsect1>

  <refsect1 id='caveats'>
    <title>CAVEATS</title>
    <para>
      You may not add a user to a NIS or LDAP group. This must be
      performed on the corresponding server.
    </para>

    <para>
      Similarly, if the username already exists in an external user
      database such as NIS or LDAP, <command>useradd</command> will deny
      the user account creation request.
    </para>

    <para>
      It is usually recommended to only use usernames that begin with a lower case letter or an underscore,
      followed by lower case letters, digits, underscores, or dashes.
      They can end with a dollar sign.
      In regular expression terms: [a-z_][a-z0-9_-]*[$]?
    </para>
    <para>
      On Debian, the only constraints are that usernames must neither start
      with a dash ('-') nor plus ('+') nor tilde ('~') nor contain a
      colon (':'), a comma (','), or a whitespace (space: ' ',
      end of line: '\n', tabulation: '\t', etc.). Note that using a slash
      ('/') may break the default algorithm for the definition of the
      user's home directory.
    </para>
    <para>
      Usernames may only be up to 32 characters long.
    </para>
  </refsect1>

  <refsect1 id='configuration'>
    <title>CONFIGURATION</title>
    <para>
      The following configuration variables in
      <filename>/etc/login.defs</filename> change the behavior of this
      tool:
    </para>
    <variablelist>
      &CREATE_HOME;
      &GID_MAX; <!-- documents also GID_MIN -->
      &MAIL_DIR;
      &MAX_MEMBERS_PER_GROUP;
      &PASS_MAX_DAYS;
      &PASS_MIN_DAYS;
      &PASS_WARN_AGE;
      &SUB_GID_COUNT; <!-- documents also SUB_GID_MAX and SUB_GID_MIN -->
      &SUB_UID_COUNT; <!-- documents also SUB_UID_MAX and SUB_UID_MIN -->
      &SYS_GID_MAX; <!-- documents also SYS_GID_MIN -->
      &SYS_UID_MAX; <!-- documents also SYS_UID_MIN -->
      &TCB_AUTH_GROUP;
      &TCB_SYMLINKS;
      &UID_MAX; <!-- documents also UID_MIN -->
      &UMASK;
      &USE_TCB;
      &USERGROUPS_ENAB;
    </variablelist>
  </refsect1>

  <refsect1 id='files'>
    <title>FILES</title>
    <variablelist>
      <varlistentry>
	<term><filename>/etc/passwd</filename></term>
	<listitem>
	  <para>User account information.</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><filename>/etc/shadow</filename></term>
	<listitem>
	  <para>Secure user account information.</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><filename>/etc/group</filename></term>
	<listitem>
	  <para>Group account information.</para>
	</listitem>
      </varlistentry>
      <varlistentry condition="gshadow">
	<term><filename>/etc/gshadow</filename></term>
	<listitem>
	  <para>Secure group account information.</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><filename>/etc/default/useradd</filename></term>
	<listitem>
	  <para>Default values for account creation.</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><filename>/etc/skel/</filename></term>
	<listitem>
	  <para>Directory containing default files.</para>
	</listitem>
      </varlistentry>
      <varlistentry condition="subids">
	<term><filename>/etc/subgid</filename></term>
	<listitem>
	  <para>Per user subordinate group IDs.</para>
	</listitem>
      </varlistentry>
      <varlistentry condition="subids">
	<term><filename>/etc/subuid</filename></term>
	<listitem>
	  <para>Per user subordinate user IDs.</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><filename>/etc/login.defs</filename></term>
	<listitem>
	  <para>Shadow password suite configuration.</para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1 id='exit_values'>
    <title>EXIT VALUES</title>
    <para>
      The <command>useradd</command> command exits with the following values:
      <variablelist>
	<varlistentry>
	  <term><replaceable>0</replaceable></term>
	  <listitem>
	    <para>success</para>
	  </listitem>
	</varlistentry>
	<varlistentry>
	  <term><replaceable>1</replaceable></term>
	  <listitem>
	    <para>can't update password file</para>
	  </listitem>
	</varlistentry>
	<varlistentry>
	  <term><replaceable>2</replaceable></term>
	  <listitem>
	    <para>invalid command syntax</para>
	  </listitem>
	</varlistentry>
	<varlistentry>
	  <term><replaceable>3</replaceable></term>
	  <listitem>
	    <para>invalid argument to option</para>
	  </listitem>
	</varlistentry>
	<varlistentry>
	  <term><replaceable>4</replaceable></term>
	  <listitem>
	    <para>UID already in use (and no <option>-o</option>)</para>
	  </listitem>
	</varlistentry>
	<varlistentry>
	  <term><replaceable>6</replaceable></term>
	  <listitem>
	    <para>specified group doesn't exist</para>
	  </listitem>
	</varlistentry>
	<varlistentry>
	  <term><replaceable>9</replaceable></term>
	  <listitem>
	    <para>username already in use</para>
	  </listitem>
	</varlistentry>
	<varlistentry>
	  <term><replaceable>10</replaceable></term>
	  <listitem>
	    <para>can't update group file</para>
	  </listitem>
	</varlistentry>
	<varlistentry>
	  <term><replaceable>12</replaceable></term>
	  <listitem>
	    <para>can't create home directory</para>
	  </listitem>
	</varlistentry>
	<varlistentry>
	  <term><replaceable>14</replaceable></term>
	  <listitem>
	    <para>can't update SELinux user mapping</para>
	  </listitem>
	</varlistentry>
      </variablelist>
    </para>
  </refsect1>

  <refsect1 id='see_also'>
    <title>SEE ALSO</title>
    <para>
      <citerefentry>
	<refentrytitle>chfn</refentrytitle><manvolnum>1</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>chsh</refentrytitle><manvolnum>1</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>passwd</refentrytitle><manvolnum>1</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>crypt</refentrytitle><manvolnum>3</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>groupadd</refentrytitle><manvolnum>8</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>groupdel</refentrytitle><manvolnum>8</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>groupmod</refentrytitle><manvolnum>8</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>login.defs</refentrytitle><manvolnum>5</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>newusers</refentrytitle><manvolnum>8</manvolnum>
      </citerefentry>,
      <phrase condition="subids">
	<citerefentry>
	  <refentrytitle>subgid</refentrytitle><manvolnum>5</manvolnum>
	</citerefentry>,
	<citerefentry>
	  <refentrytitle>subuid</refentrytitle><manvolnum>5</manvolnum>
	</citerefentry>,
      </phrase>
      <citerefentry>
	<refentrytitle>userdel</refentrytitle><manvolnum>8</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>usermod</refentrytitle><manvolnum>8</manvolnum>
      </citerefentry>.
    </para>
  </refsect1>
</refentry>