shadow/man/passwd.5.xml

<?xml version="1.0" encoding="UTF-8"?>
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<refentry id='passwd.5'>
  <!-- $Id$ -->
  <refmeta>
    <refentrytitle>passwd</refentrytitle>
    <manvolnum>5</manvolnum>
    <refmiscinfo class="sectdesc">File Formats and Conversions</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>
      The encrypted password field may be blank, 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. 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. 
      If the <emphasis>password</emphasis> field is any other string, then
      it will be treated as an encrypted password, as specified by
      <citerefentry><refentrytitle>crypt</refentrytitle>
      <manvolnum>3</manvolnum></citerefentry>.

    </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>
    </variablelist>
  </refsect1>

  <refsect1 id='see_also'>
    <title>SEE ALSO</title>
    <para>
      <citerefentry>
	<refentrytitle>getent</refentrytitle><manvolnum>1</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>login</refentrytitle><manvolnum>1</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>passwd</refentrytitle><manvolnum>1</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>su</refentrytitle><manvolnum>1</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>crypt</refentrytitle><manvolnum>3</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>getpwnam</refentrytitle><manvolnum>3</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>shadow</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>