shadow/man/shadow.5.xml

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<?xml version="1.0" encoding="UTF-8"?>
<refentry id='shadow.5'>
<!-- $Id$ -->
<refmeta>
<refentrytitle>shadow</refentrytitle>
<manvolnum>5</manvolnum>
<refmiscinfo class="sectdesc">File Formats and Conversions</refmiscinfo>
</refmeta>
<refnamediv id='name'>
<refname>shadow</refname>
<refpurpose>encrypted password file</refpurpose>
</refnamediv>
<refsect1 id='description'>
<title>DESCRIPTION</title>
<para>
<emphasis remap='I'>shadow</emphasis> contains the encrypted password
information for user's accounts and optional the password aging
information. Included is:
</para>
<itemizedlist mark='bullet'>
<listitem>
<para>login name</para>
</listitem>
<listitem>
<para>encrypted password</para>
</listitem>
<listitem>
<para>days since Jan 1, 1970 that password was last changed</para>
</listitem>
<listitem>
<para>days before password may be changed</para>
</listitem>
<listitem>
<para>days after which password must be changed</para>
</listitem>
<listitem>
<para>days before password is to expire that user is warned</para>
</listitem>
<listitem>
<para>days after password expires that account is disabled</para>
</listitem>
<listitem>
<para>days since Jan 1, 1970 that account is disabled</para>
</listitem>
<listitem>
<para>a reserved field</para>
</listitem>
</itemizedlist>
<para>
The password field must be filled. The encrypted password consists of
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13 to 24 characters from the 64 character alphabet a thru z, A thru
Z, 0 thru 9, \. and /. Optionally it can start with a "$" character.
This means the encrypted password was generated using another (not
DES) algorithm. For example if it starts with "$1$" it means the
MD5-based algorithm was used.
</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 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, subject to
<citerefentry><refentrytitle>pam</refentrytitle>
<manvolnum>7</manvolnum></citerefentry>.
</para>
<para>
The date of the last password change is given as the number of days
since Jan 1, 1970. The password may not be changed again until the
proper number of days have passed, and must be changed before the
maximum number of days. If the minimum number of days required is
greater than the maximum number of day allowed, this password may not
be changed by the user.
</para>
<para>
An account is considered to be inactive and is disabled if the
password is not changed within the specified number of days after the
password expires. An account will also be disabled on the specified
day regardless of other password expiration information.
</para>
<para>
This information supersedes any password or password age information
present in <filename>/etc/passwd</filename>.
</para>
<para>
This file must not be readable by regular users if password security
is to be maintained.
</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>Secure user account information.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id='see_also'>
<title>SEE ALSO</title>
<para><citerefentry>
<refentrytitle>chage</refentrytitle><manvolnum>1</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>login</refentrytitle><manvolnum>1</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>su</refentrytitle><manvolnum>1</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>passwd</refentrytitle><manvolnum>1</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>passwd</refentrytitle><manvolnum>5</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>pwconv</refentrytitle><manvolnum>8</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>pwunconv</refentrytitle><manvolnum>8</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>sulogin</refentrytitle><manvolnum>8</manvolnum>
</citerefentry>.
</para>
</refsect1>
</refentry>