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<?xml version="1.0" encoding="UTF-8"?>
<!--
   Copyright (c) 1989 - 1990, Julianne Frances Haugh
   Copyright (c) 2007 - 2008, 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" [
<!-- SHADOW-CONFIG-HERE -->
]>
<refentry id='passwd.5'>
  <!-- $Id$ -->
  <refentryinfo>
    <author>
      <firstname>Julianne Frances</firstname>
      <surname>Haugh</surname>
      <contrib>Creation, 1989</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>passwd</refentrytitle>
    <manvolnum>5</manvolnum>
    <refmiscinfo class="sectdesc">File Formats and Conversions</refmiscinfo>
    <refmiscinfo class="source">shadow-utils</refmiscinfo>
    <refmiscinfo class="version">&SHADOW_UTILS_VERSION;</refmiscinfo>
  </refmeta>
  <refnamediv id='name'>
    <refname>passwd</refname>
    <refpurpose>the password file</refpurpose>
  </refnamediv>

  <refsect1 id='description'>
    <title>DESCRIPTION</title>
    <para>
      <filename>/etc/passwd</filename> contains one line for each
      user account, with seven fields delimited by colons
      (<quote>:</quote>).
      These fields are:
    </para>
    <itemizedlist mark='bullet'>
      <listitem>
	<para>login name</para>
      </listitem>
      <listitem>
	<para>optional encrypted password</para>
      </listitem>
      <listitem>
	<para>numerical user ID</para>
      </listitem>
      <listitem>
	<para>numerical group ID</para>
      </listitem>
      <listitem>
	<para>user name or comment field</para>
      </listitem>
      <listitem>
	<para>user home directory</para>
      </listitem>
      <listitem>
	<para>optional user command interpreter</para>
      </listitem>
    </itemizedlist>

    <para>
      If the <emphasis>password</emphasis> field is a lower-case
      <quote>x</quote>, then the encrypted password is actually stored in the
      <citerefentry><refentrytitle>shadow</refentrytitle>
      <manvolnum>5</manvolnum></citerefentry> file instead; there
      <emphasis>must</emphasis> be a corresponding line in the
      <filename>/etc/shadow</filename> file, or else the user account is invalid. 
    </para>

    <para>
      The encrypted <emphasis>password</emphasis> field may be empty,
      in which case no password is required to authenticate as the
      specified login name. However, some applications which read the
      <filename>/etc/passwd</filename> file may decide not to permit
      <emphasis>any</emphasis> access at all if the
      <emphasis>password</emphasis> field is blank.
    </para>

    <para>
      A <emphasis>password</emphasis> field which starts with an
      exclamation mark means that the password is locked.  The
      remaining characters on the line represent the
      <emphasis>password</emphasis> field before the password was
      locked.
    </para>

    <para>
      Refer to <citerefentry><refentrytitle>crypt</refentrytitle>
      <manvolnum>3</manvolnum></citerefentry> for details on how
      this string is interpreted.
    </para>
    <para>
      If the password field contains some string that is not a valid
      result of <citerefentry><refentrytitle>crypt</refentrytitle>
      <manvolnum>3</manvolnum></citerefentry>, for instance ! or *,
      the user will not be able to use a unix password to log in
      (but the user may log in the system by other means).
    </para>
    <para>
      The comment field is used by various system utilities, such as
      <citerefentry><refentrytitle>finger</refentrytitle>
      <manvolnum>1</manvolnum></citerefentry>.
    </para>

    <para>
      The home directory field provides the name of the initial working
      directory. The <command>login</command> program uses this information
      to set the value of the <envar>$HOME</envar> environmental variable.
    </para>

    <para>
      The command interpreter field provides the name of the user's command
      language interpreter, or the name of the initial program to execute. 
      The <command>login</command> program uses this information to set the
      value of the <envar>$SHELL</envar> environmental variable. If this
      field is empty, it defaults to the value <filename>/bin/sh</filename>.
    </para>
  </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>optional encrypted password file</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><filename>/etc/passwd-</filename></term>
	<listitem>
	  <para>Backup file for /etc/passwd.</para>
	  <para>
	    Note that this file is used by the tools of the shadow
	    toolsuite, but not by all user and password management tools.
	  </para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1 id='see_also'>
    <title>SEE ALSO</title>
    <para>
      <citerefentry>
	<refentrytitle>crypt</refentrytitle><manvolnum>3</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>getent</refentrytitle><manvolnum>1</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>getpwnam</refentrytitle><manvolnum>3</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>login</refentrytitle><manvolnum>1</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>passwd</refentrytitle><manvolnum>1</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>pwck</refentrytitle><manvolnum>8</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>pwconv</refentrytitle><manvolnum>8</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>pwunconv</refentrytitle><manvolnum>8</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>shadow</refentrytitle><manvolnum>5</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>su</refentrytitle><manvolnum>1</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>sulogin</refentrytitle><manvolnum>8</manvolnum>
      </citerefentry>.
    </para>
  </refsect1>
</refentry>