shadow/man/chpasswd.8.xml

<?xml version="1.0" encoding="UTF-8"?>
<!--
   Copyright (c) 1991       , 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 ENCRYPT_METHOD        SYSTEM "login.defs.d/ENCRYPT_METHOD.xml">
<!ENTITY MD5_CRYPT_ENAB        SYSTEM "login.defs.d/MD5_CRYPT_ENAB.xml">
<!ENTITY SHA_CRYPT_MIN_ROUNDS  SYSTEM "login.defs.d/SHA_CRYPT_MIN_ROUNDS.xml">
<!-- SHADOW-CONFIG-HERE -->
]>

<refentry id='chpasswd.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>chpasswd</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>chpasswd</refname>
    <refpurpose>update passwords in batch mode</refpurpose>
  </refnamediv>

  <refsynopsisdiv id='synopsis'>
    <cmdsynopsis>
      <command>chpasswd</command>
      <arg choice='opt'>
	<replaceable>options</replaceable>
      </arg>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1 id='description'>
    <title>DESCRIPTION</title>
    <para>
      The <command>chpasswd</command> command reads a list of user name and
      password pairs from standard input and uses this information to update
      a group of existing users. Each line is of the format:
    </para>
    <para>
      <emphasis remap='I'>user_name</emphasis>:<emphasis
      remap='I'>password</emphasis>
    </para>
    <para>
      By default the passwords must be supplied in clear-text, and are
      encrypted by <command>chpasswd</command>.
      Also the password age will be updated, if present.
    </para>
    <para condition="no_pam">
      The default encryption algorithm can be defined for the system with
      the <option>ENCRYPT_METHOD</option> or
      <option>MD5_CRYPT_ENAB</option> variables of
      <filename>/etc/login.defs</filename>, and can be overwitten with the
      <option>-e</option>, <option>-m</option>, or <option>-c</option>
      options.
    </para>
    <para condition="pam">
      By default, passwords are encrypted by PAM, but (even if not
      recommended) you can select a different encryption method with the
      <option>-e</option>, <option>-m</option>, or <option>-c</option>
      options.
    </para>
    <para>
      <phrase condition="pam">Except when PAM is used to encrypt the
      passwords,</phrase> <command>chpasswd</command> first updates all the
      passwords in memory, and then commits all the changes to disk if no
      errors occured for any user.
    </para>
    <para condition="pam">
      When PAM is used to encrypt the passwords (and update the passwords in
      the system database) then if a password cannot be updated
      <command>chpasswd</command> continues updating the passwords of the
      next users, and will return an error code on exit.
    </para>
    <para>
      This command is intended to be used in a large system environment
      where many accounts are created at a single time.
    </para>
  </refsect1>

  <refsect1 id='options'>
    <title>OPTIONS</title>
    <para>
      The options which apply to the <command>chpasswd</command> command
      are:
    </para>
    <variablelist remap='IP'>
      <varlistentry>
	<term>
	  <option>-c</option>, <option>--crypt-method</option>&nbsp;<replaceable>METHOD</replaceable>
	</term>
	<listitem>
	  <para>Use the specified method to encrypt the passwords.</para>
	  <para condition="no_sha_crypt">
	    The available methods are DES, MD5, and NONE.
	  </para>
	  <para condition="sha_crypt">
	    The available methods are DES, MD5, NONE, and SHA256 or SHA512
	    if your libc support these methods.
	  </para>
	  <para condition="pam">
	    By default, PAM is used to encrypt the passwords.
	  </para>
	  <para condition="no_pam">
	    By default (if none of the <option>-c</option>,
	    <option>-m</option>, or <option>-e</option> options are
	    specified), the encryption method is defined by the 
	    <option>ENCRYPT_METHOD</option> or
	    <option>MD5_CRYPT_ENAB</option> variables of
	    <filename>/etc/login.defs</filename>.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><option>-e</option>, <option>--encrypted</option></term>
	<listitem>
	  <para>Supplied passwords are in encrypted form.</para>
	</listitem>
      </varlistentry>
    </variablelist>
    <variablelist remap='IP'>
      <varlistentry>
	<term><option>-h</option>, <option>--help</option></term>
	<listitem>
	  <para>Display help message and exit.</para>
	</listitem>
      </varlistentry>
    </variablelist>
    <variablelist remap='IP'>
      <varlistentry>
	<term><option>-m</option>, <option>--md5</option></term>
	<listitem>
	  <para>
	    Use MD5 encryption instead of DES when the supplied passwords are
	    not encrypted.
	  </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 condition="sha_crypt">
	<term>
	  <option>-s</option>, <option>--sha-rounds</option>&nbsp;<replaceable>ROUNDS</replaceable>
	</term>
	<listitem>
	  <para>
	    Use the specified number of rounds to encrypt the passwords.
	  </para>
	  <para>
	    The value 0 means that the system will choose the default
	    number of rounds for the crypt method (5000).
	  </para>
	  <para>
	    A minimal value of 1000 and a maximal value of 999,999,999
	    will be enforced.
	  </para>
	  <para>
	    You can only use this option with the SHA256 or SHA512
	    crypt method.
	  </para>
	  <para>
	    By default, the number of rounds is defined by the
	    <option>SHA_CRYPT_MIN_ROUNDS</option> and
	    <option>SHA_CRYPT_MAX_ROUNDS</option> variables in
	    <filename>/etc/login.defs</filename>.
	  </para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1 id='caveats'>
    <title>CAVEATS</title>
    <para>
      Remember to set permissions or umask to prevent readability of
      unencrypted files by other users.
    </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 condition="no_pam">
      &ENCRYPT_METHOD;
      &MD5_CRYPT_ENAB;
    </variablelist>
    <variablelist>
      &SHA_CRYPT_MIN_ROUNDS; <!--documents also SHA_CRYPT_MAX_ROUNDS-->
    </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/login.defs</filename></term>
	<listitem>
	  <para>Shadow password suite configuration.</para>
	</listitem>
      </varlistentry>
      <varlistentry condition="pam">
	<term><filename>/etc/pam.d/chpasswd</filename></term>
	<listitem>
	  <para>PAM configuration for <command>chpasswd</command>.</para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1 id='see_also'>
    <title>SEE ALSO</title>
    <para>
      <citerefentry>
	<refentrytitle>passwd</refentrytitle><manvolnum>1</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>newusers</refentrytitle><manvolnum>8</manvolnum>
      </citerefentry>,
      <phrase>
	<citerefentry>
	  <refentrytitle>login.defs</refentrytitle><manvolnum>5</manvolnum>
	</citerefentry>,
      </phrase>
      <citerefentry>
	<refentrytitle>useradd</refentrytitle><manvolnum>8</manvolnum>
      </citerefentry>.
    </para>
  </refsect1>
</refentry>