291 lines
8.8 KiB
XML
291 lines
8.8 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!--
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SPDX-FileCopyrightText: 1989 - 1990, Julianne Frances Haugh
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SPDX-FileCopyrightText: 2007 - 2009, Nicolas François
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SPDX-License-Identifier: BSD-3-Clause
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-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
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<!-- SHADOW-CONFIG-HERE -->
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]>
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<refentry id='shadow.5'>
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<!-- $Id$ -->
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<refentryinfo>
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<author>
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<firstname>Julianne Frances</firstname>
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<surname>Haugh</surname>
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<contrib>Creation, 1989</contrib>
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</author>
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<author>
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<firstname>Thomas</firstname>
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<surname>Kłoczko</surname>
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<email>kloczek@pld.org.pl</email>
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<contrib>shadow-utils maintainer, 2000 - 2007</contrib>
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</author>
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<author>
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<firstname>Nicolas</firstname>
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<surname>François</surname>
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<email>nicolas.francois@centraliens.net</email>
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<contrib>shadow-utils maintainer, 2007 - now</contrib>
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</author>
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</refentryinfo>
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<refmeta>
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<refentrytitle>shadow</refentrytitle>
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<manvolnum>5</manvolnum>
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<refmiscinfo class="sectdesc">File Formats and Configuration Files</refmiscinfo>
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<refmiscinfo class="source">shadow-utils</refmiscinfo>
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<refmiscinfo class="version">&SHADOW_UTILS_VERSION;</refmiscinfo>
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</refmeta>
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<refnamediv id='name'>
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<refname>shadow</refname>
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<refpurpose>shadowed password file</refpurpose>
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</refnamediv>
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<refsect1 id='description'>
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<title>DESCRIPTION</title>
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<para>
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<filename>shadow</filename> is a file which contains the password
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information for the system's accounts and optional aging
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information.
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</para>
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<para>
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This file must not be readable by regular users if password security
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is to be maintained.
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</para>
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<para>
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Each line of this file contains 9 fields, separated by colons
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(<quote>:</quote>), in the following order:
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</para>
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<variablelist>
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<varlistentry>
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<term><emphasis role="bold">login name</emphasis></term>
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<listitem>
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<para>
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It must be a valid account name, which exist on the system.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><emphasis role="bold">encrypted password</emphasis></term>
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<listitem>
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<para>
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This field may be empty, in which case no passwords are
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required to authenticate as the specified login name.
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However, some applications which read the
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<filename>/etc/shadow</filename> file may decide not to permit
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any access at all if the password field is empty.
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</para>
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<para>
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A password field which starts with an exclamation mark means
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that the password is locked. The remaining characters on the
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line represent the password field before the password was
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locked.
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</para>
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<para>
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Refer to <citerefentry><refentrytitle>crypt</refentrytitle>
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<manvolnum>3</manvolnum></citerefentry> for details on how
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this string is interpreted.
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</para>
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<para>
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If the password field contains some string that is not a valid
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result of <citerefentry><refentrytitle>crypt</refentrytitle>
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<manvolnum>3</manvolnum></citerefentry>, for instance ! or *,
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the user will not be able to use a unix password to log in
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(but the user may log in the system by other means).
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<emphasis role="bold">date of last password change</emphasis>
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</term>
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<listitem>
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<para>
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The date of the last password change, expressed as the number
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of days since Jan 1, 1970 00:00 UTC.
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</para>
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<para>
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The value 0 has a special meaning, which is that the user
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should change her password the next time she will log in the
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system.
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</para>
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<para>
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An empty field means that password aging features are
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disabled.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><emphasis role="bold">minimum password age</emphasis></term>
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<listitem>
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<para>
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The minimum password age is the number of days the user will
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have to wait before she will be allowed to change her password
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again.
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</para>
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<para>
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An empty field and value 0 mean that there is no minimum
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password age.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><emphasis role="bold">maximum password age</emphasis></term>
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<listitem>
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<para>
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The maximum password age is the number of days after which the
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user will have to change her password.
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</para>
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<para>
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After this number of days is elapsed, the password may still
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be valid. The user should be asked to change her password the
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next time she will log in.
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</para>
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<para>
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An empty field means that there are no maximum password age,
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no password warning period, and no password inactivity period
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(see below).
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</para>
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<para>
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If the maximum password age is lower than the minimum password
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age, the user cannot change her password.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<emphasis role="bold">password warning period</emphasis>
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</term>
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<listitem>
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<para>
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The number of days before a password is going to expire (see
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the maximum password age above) during which the user should
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be warned.
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</para>
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<para>
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An empty field and value 0 mean that there are no password
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warning period.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<emphasis role="bold">password inactivity period</emphasis>
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</term>
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<listitem>
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<para>
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The number of days after a password has expired (see the
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maximum password age above) during which the password should
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still be accepted (and the user should update her password
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during the next login).
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</para>
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<para>
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After expiration of the password and this expiration period is
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elapsed, no login is possible for the user. The user should contact
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her administrator.
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</para>
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<para>
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An empty field means that there are no enforcement of an
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inactivity period.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<emphasis role="bold">account expiration date</emphasis>
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</term>
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<listitem>
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<para>
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The date of expiration of the account, expressed as the number
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of days since Jan 1, 1970 00:00 UTC.
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</para>
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<para>
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Note that an account expiration differs from a password
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expiration. In case of an account expiration, the user shall
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not be allowed to login. In case of a password expiration,
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the user is not allowed to login using her password.
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</para>
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<para>
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An empty field means that the account will never expire.
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</para>
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<para>
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The value 0 should not be used as it is interpreted as either
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an account with no expiration, or as an expiration on Jan 1,
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1970.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><emphasis role="bold">reserved field</emphasis></term>
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<listitem>
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<para>This field is reserved for future use.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1 id='files'>
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<title>FILES</title>
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<variablelist>
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<varlistentry>
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<term><filename>/etc/passwd</filename></term>
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<listitem>
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<para>User account information.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>/etc/shadow</filename></term>
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<listitem>
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<para>Secure user account information.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>/etc/shadow-</filename></term>
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<listitem>
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<para>Backup file for /etc/shadow.</para>
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<para>
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Note that this file is used by the tools of the shadow
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toolsuite, but not by all user and password management tools.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1 id='see_also'>
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<title>SEE ALSO</title>
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<para>
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<citerefentry>
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<refentrytitle>chage</refentrytitle><manvolnum>1</manvolnum>
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</citerefentry>,
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<citerefentry>
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<refentrytitle>login</refentrytitle><manvolnum>1</manvolnum>
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</citerefentry>,
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<citerefentry>
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<refentrytitle>passwd</refentrytitle><manvolnum>1</manvolnum>
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</citerefentry>,
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<citerefentry>
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<refentrytitle>passwd</refentrytitle><manvolnum>5</manvolnum>
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</citerefentry>,
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<citerefentry>
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<refentrytitle>pwck</refentrytitle><manvolnum>8</manvolnum>
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</citerefentry>,
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<citerefentry>
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<refentrytitle>pwconv</refentrytitle><manvolnum>8</manvolnum>
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</citerefentry>,
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<citerefentry>
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<refentrytitle>pwunconv</refentrytitle><manvolnum>8</manvolnum>
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</citerefentry>,
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<citerefentry>
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<refentrytitle>su</refentrytitle><manvolnum>1</manvolnum>
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</citerefentry>,
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<citerefentry>
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<refentrytitle>sulogin</refentrytitle><manvolnum>8</manvolnum>
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</citerefentry>.
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</para>
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</refsect1>
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</refentry>
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