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shadow/man/chpasswd.8.xml

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<?xml version="1.0" encoding="UTF-8"?>
<!--
Copyright (c) 1991 , Julianne Frances Haugh
Copyright (c) 2007 - 2009, Nicolas François
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<!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">
]>
<refentry id='chpasswd.8'>
<!-- $Id$ -->
<refmeta>
<refentrytitle>chpasswd</refentrytitle>
<manvolnum>8</manvolnum>
<refmiscinfo class="sectdesc">System Management Commands</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>
<refsect2 condition="no_pam">
<para>
By default the supplied password must be in clear-text, and is
encrypted by <command>chpasswd</command>.
Also the password age will be updated, if present.
</para>
<para>
The default encryption algorithm can be defined for the system with
the ENCRYPT_METHOD variable of <filename>/etc/login.defs</filename>,
and can be overwiten with the <option>-e</option>,
<option>-m</option>, or <option>-c</option> options.
</para>
<para>
<command>chpasswd</command> first update the password in memory,
and then commit all the changes to disk if no errors occured for
any users.
</para>
</refsect2>
<refsect2 condition="pam">
<para>
The supplied passwords must be in clear-text.
</para>
<para>
PAM is used to update the password in the system database
according to the PAM chpasswd configuration.
</para>
<para>
When <command>chpasswd</command> fails to update a password, it
continues updating the passwords of the next users, and will
return an error code on exit.
</para>
</refsect2>
<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' condition="no_pam">
<varlistentry>
<term><option>-c</option>, <option>--crypt-method</option></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>
</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' condition="no_pam">
<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 condition="sha_crypt">
<term><option>-s</option>, <option>--sha-rounds</option></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
SHA_CRYPT_MIN_ROUNDS and SHA_CRYPT_MAX_ROUNDS 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' condition="no_pam">
<title>CONFIGURATION</title>
<para>
The following configuration variables in
<filename>/etc/login.defs</filename> change the behavior of this
tool:
</para>
<variablelist>
&ENCRYPT_METHOD;
&MD5_CRYPT_ENAB;
&SHA_CRYPT_MIN_ROUNDS; <!--documents also SHA_CRYPT_MAX_ROUNDS-->
</variablelist>
</refsect1>
<refsect1 id='files'>
<title>FILES</title>
<variablelist>
<varlistentry condition="no_pam">
<term><filename>/etc/passwd</filename></term>
<listitem>
<para>User account information.</para>
</listitem>
</varlistentry>
<varlistentry condition="no_pam">
<term><filename>/etc/shadow</filename></term>
<listitem>
<para>Secure user account information.</para>
</listitem>
</varlistentry>
<varlistentry condition="no_pam">
<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>,
<citerefentry condition="no_pam">
<refentrytitle>login.defs</refentrytitle><manvolnum>5</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>useradd</refentrytitle><manvolnum>8</manvolnum>
</citerefentry>.
</para>
</refsect1>
</refentry>
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