<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
"http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd">
<refentry id='login.1'>
- <!-- $Id: login.1.xml,v 1.10 2005/07/10 20:10:09 kloczek Exp $ -->
+ <!-- $Id: login.1.xml,v 1.23 2005/12/15 14:50:15 kloczek Exp $ -->
<refmeta>
- <refentrytitle>LOGIN</refentrytitle>
+ <refentrytitle>login</refentrytitle>
<manvolnum>1</manvolnum>
<refmiscinfo class="sectdesc">User Commands</refmiscinfo>
</refmeta>
<arg choice='plain'>-r <replaceable>host</replaceable></arg>
</cmdsynopsis>
</refsynopsisdiv>
-
+
<refsect1 id='description'>
<title>DESCRIPTION</title>
- <para><command>login</command> is used to establish a new session with the
+ <para>
+ <command>login</command> is used to establish a new session with the
system. It is normally invoked automatically by responding to the
<emphasis remap='I'>login:</emphasis> prompt on the user´s
terminal. <command>login</command> may be special to the shell and may
execute <command>login</command> from any shell but the login shell
will produce an error message.
</para>
-
- <para>The user is then prompted for a password, where appropriate.
- Echoing is disabled to prevent revealing the password. Only a small
- number of password failures are permitted before
- <command>login</command> exits and the communications link is severed.
+
+ <para>
+ The user is then prompted for a password, where appropriate. Echoing
+ is disabled to prevent revealing the password. Only a small number of
+ password failures are permitted before <command>login</command> exits
+ and the communications link is severed.
</para>
-
- <para>If password aging has been enabled for your account, you may be
+
+ <para>
+ If password aging has been enabled for your account, you may be
prompted for a new password before proceeding. You will be forced to
provide your old password and the new password before continuing.
Please refer to <citerefentry>
<refentrytitle>passwd</refentrytitle><manvolnum>1</manvolnum>
</citerefentry> for more information.
</para>
-
- <para>After a successful login, you will be informed of any system
- messages and the presence of mail. You may turn off the printing of
- the system message file, <filename>/etc/motd</filename>, by creating a
- zero-length file <markup>.hushlogin</markup> in your login directory.
- The mail message will be one of "<emphasis remap='B'>You have new
- mail.</emphasis> ", "<emphasis remap='B'>You have mail.</emphasis>",
- or "<emphasis remap='B'>No Mail.</emphasis> "according to the
- condition of your mailbox.
+
+ <para>
+ After a successful login, you will be informed of any system messages
+ and the presence of mail. You may turn off the printing of the system
+ message file, <filename>/etc/motd</filename>, by creating a
+ zero-length file <filename>.hushlogin</filename> in your login directory.
+ The mail message will be one of "<emphasis>You have new
+ mail.</emphasis>", "<emphasis>You have mail.</emphasis>", or
+ "<emphasis>No Mail.</emphasis> "according to the condition of your
+ mailbox.
</para>
-
- <para>Your user and group ID will be set according to their values in
- the <filename>/etc/passwd</filename> file. The value for <emphasis
- remap='B'>$HOME</emphasis>, <emphasis remap='B'>$SHELL</emphasis>,
- <emphasis remap='B'>$PATH</emphasis>, <emphasis remap='B'>$LOGNAME</emphasis>,
- and <emphasis remap='B'>$MAIL</emphasis> are set according to the
- appropriate fields in the password entry. Ulimit, umask and nice
+
+ <para>
+ Your user and group ID will be set according to their values in the
+ <filename>/etc/passwd</filename> file. The value for
+ <envar>$HOME</envar>, <envar>$SHELL</envar>, <envar>$PATH</envar>,
+ <envar>$LOGNAME</envar>, and <envar>$MAIL</envar> are set according
+ to the appropriate fields in the password entry. Ulimit, umask and nice
values may also be set according to entries in the GECOS field.
</para>
-
- <para>On some installations, the environmental variable <emphasis
- remap='B'>$TERM</emphasis> will be initialized to the terminal type on
+
+ <para>
+ On some installations, the environmental variable
+ <envar>$TERM</envar> will be initialized to the terminal type on
your tty line, as specified in <filename>/etc/ttytype</filename>.
</para>
-
- <para>An initialization script for your command interpreter may also be
+
+ <para>
+ An initialization script for your command interpreter may also be
executed. Please see the appropriate manual section for more
- information on
- this function.
+ information on this function.
</para>
-
- <para>A subsystem login is indicated by the presence of a "*" as the
- first character of the login shell. The given home directory will be
- used as the root of a new file system which the user is actually
- logged into.
+
+ <para>
+ A subsystem login is indicated by the presence of a "*" as the first
+ character of the login shell. The given home directory will be used as
+ the root of a new file system which the user is actually logged into.
</para>
- <para>The <command>login</command> program is NOT responsible for
- removing users from the utmp file. It is the responsibility of
- <refentrytitle>getty</refentrytitle><manvolnum>8</manvolnum> and
- <refentrytitle>init</refentrytitle><manvolnum>8</manvolnum> to clean
- up apparent ownership of a terminal session. If you use
- <command>login</command> from the shell prompt without
- <command>exec</command>, the user you use will continue to appear to
- be logged in even after you log out of the "subsession".
+ <para>
+ The <command>login</command> program is NOT responsible for removing
+ users from the utmp file. It is the responsibility of
+ <citerefentry><refentrytitle>getty</refentrytitle>
+ <manvolnum>8</manvolnum></citerefentry> and
+ <citerefentry><refentrytitle>init</refentrytitle>
+ <manvolnum>8</manvolnum></citerefentry> to clean up apparent ownership
+ of a terminal session. If you use <command>login</command> from the
+ shell prompt without <command>exec</command>, the user you use will
+ continue to appear to be logged in even after you log out of the
+ "subsession".
</para>
</refsect1>
-
+
<refsect1 id='options'>
<title>OPTIONS</title>
<variablelist remap='IP'>
<varlistentry>
- <term>
- <option>-f</option>
- </term>
- <listitem>
-
<para>Do not perform authentication, user is preauthenticated.
- </para>
- </listitem>
+ <term>
+ <option>-f</option>
+ </term>
+ <listitem>
+ <para>Do not perform authentication, user is preauthenticated.
+ </para>
+ </listitem>
</varlistentry>
<varlistentry>
- <term>
- <option>-h</option>
- </term>
- <listitem>
-
<para>Name of the remote host for this login.</para>
- </listitem>
+ <term>
+ <option>-h</option>
+ </term>
+ <listitem>
+ <para>Name of the remote host for this login.</para>
+ </listitem>
</varlistentry>
<varlistentry>
- <term>
- <option>-p</option>
- </term>
- <listitem>
-
<para>Preserve environment.</para>
- </listitem>
+ <term>
+ <option>-p</option>
+ </term>
+ <listitem>
+ <para>Preserve environment.</para>
+ </listitem>
</varlistentry>
<varlistentry>
- <term>
- <option>-r</option>
- </term>
- <listitem>
-
<para>Perform autologin protocol for rlogin.</para>
- </listitem>
+ <term>
+ <option>-r</option>
+ </term>
+ <listitem>
+ <para>Perform autologin protocol for rlogin.</para>
+ </listitem>
</varlistentry>
</variablelist>
-
- <para>The <option>-r</option>, <option>-h</option> and
- <option>-f</option> options are only used when
- <command>login</command> is invoked by root.
+
+ <para>
+ The <option>-r</option>, <option>-h</option> and <option>-f</option>
+ options are only used when <command>login</command> is invoked by
+ root.
</para>
</refsect1>
-
+
<refsect1 id='caveats'>
<title>CAVEATS</title>
<para>
This version of <command>login</command> has many compilation options,
only some of which may be in use at any particular site.
</para>
-
+
<para>The location of files is subject to differences in system
configuration.
</para>
+
+ <para>
+ The <command>login</command> program is NOT responsible for removing
+ users from the utmp file. It is the responsibility of <citerefentry>
+ <refentrytitle>getty</refentrytitle><manvolnum>8</manvolnum>
+ </citerefentry> and <citerefentry>
+ <refentrytitle>init</refentrytitle><manvolnum>8</manvolnum>
+ </citerefentry> to clean up apparent ownership of a terminal session.
+ If you use <command>login</command> from the shell prompt without
+ <command>exec</command>, the user you use will continue to appear to
+ be logged in even after you log out of the "subsession".
+ </para>
+
+ <para>
+ As any program, <command>login</command> appearance could be faked.
+ If non-trusted users have a physical access to the machine, an
+ attacker could use this to obtain the password of the next person
+ sitting in front of the machine. Under Linux, the SAK mecanism can be
+ used by users to initiate of a trusted path and prevent this kind of
+ attack.
+ </para>
+
</refsect1>
-
+
<refsect1 id='files'>
<title>FILES</title>
<variablelist>
<varlistentry>
- <term><filename>/var/run/utmp</filename></term>
- <listitem>list of current login sessions</listitem>
+ <term><filename>/var/run/utmp</filename></term>
+ <listitem>
+ <para>list of current login sessions</para>
+ </listitem>
</varlistentry>
<varlistentry>
- <term><filename>/var/log/wtmp</filename></term>
- <listitem>list of previous login sessions</listitem>
+ <term><filename>/var/log/wtmp</filename></term>
+ <listitem>
+ <para>list of previous login sessions</para>
+ </listitem>
</varlistentry>
<varlistentry>
- <term><filename>/etc/passwd</filename></term>
- <listitem>user account information</listitem>
+ <term><filename>/etc/passwd</filename></term>
+ <listitem>
+ <para>user account information</para>
+ </listitem>
</varlistentry>
<varlistentry>
- <term><filename>/etc/shadow</filename></term>
- <listitem>secure user account information</listitem>
+ <term><filename>/etc/shadow</filename></term>
+ <listitem>
+ <para>secure user account information</para>
+ </listitem>
</varlistentry>
<varlistentry>
- <term><filename>/etc/motd</filename></term>
- <listitem>system message of the day file</listitem>
+ <term><filename>/etc/motd</filename></term>
+ <listitem>
+ <para>system message of the day file</para>
+ </listitem>
</varlistentry>
<varlistentry>
- <term><filename>/etc/nologin</filename></term>
- <listitem>prevent non-root users from logging in</listitem>
+ <term><filename>/etc/nologin</filename></term>
+ <listitem>
+ <para>prevent non-root users from logging in</para>
+ </listitem>
</varlistentry>
<varlistentry>
- <term><filename>/etc/ttytype</filename></term>
- <listitem>list of terminal types</listitem>
+ <term><filename>/etc/ttytype</filename></term>
+ <listitem>
+ <para>list of terminal types</para>
+ </listitem>
</varlistentry>
<varlistentry>
- <term><filename>$HOME/.hushlogin</filename></term>
- <listitem>suppress printing of system messages</listitem>
+ <term><filename>$HOME/.hushlogin</filename></term>
+ <listitem>
+ <para>suppress printing of system messages</para>
+ </listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id='see_also'>
<title>SEE ALSO</title>
- <para><citerefentry>
- <refentrytitle>mail</refentrytitle><manvolnum>1</manvolnum>
+ <para>
+ <citerefentry>
+ <refentrytitle>mail</refentrytitle><manvolnum>1</manvolnum>
+ </citerefentry>,
+ <citerefentry>
+ <refentrytitle>passwd</refentrytitle><manvolnum>1</manvolnum>
</citerefentry>,
<citerefentry>
- <refentrytitle>passwd</refentrytitle><manvolnum>1</manvolnum>
+ <refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
</citerefentry>,
<citerefentry>
- <refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
+ <refentrytitle>su</refentrytitle><manvolnum>1</manvolnum>
</citerefentry>,
<citerefentry>
- <refentrytitle>su</refentrytitle><manvolnum>1</manvolnum>
+ <refentrytitle>login.defs</refentrytitle><manvolnum>5</manvolnum>
</citerefentry>,
<citerefentry>
- <refentrytitle>login.defs</refentrytitle><manvolnum>5</manvolnum>
+ <refentrytitle>nologin</refentrytitle><manvolnum>5</manvolnum>
</citerefentry>,
<citerefentry>
- <refentrytitle>nologin</refentrytitle><manvolnum>5</manvolnum>
+ <refentrytitle>passwd</refentrytitle><manvolnum>5</manvolnum>
</citerefentry>,
<citerefentry>
- <refentrytitle>passwd</refentrytitle><manvolnum>5</manvolnum>
+ <refentrytitle>securetty</refentrytitle><manvolnum>5</manvolnum>
</citerefentry>,
<citerefentry>
- <refentrytitle>getty</refentrytitle><manvolnum>8</manvolnum>
- </citerefentry>
+ <refentrytitle>getty</refentrytitle><manvolnum>8</manvolnum>
+ </citerefentry>.
</para>
</refsect1>
-
- <refsect1 id='author'>
- <title>AUTHOR</title>
- <para>Julianne Frances Haugh <jockgrrl@ix.netcom.com></para>
- </refsect1>
</refentry>
projects / shadow / blobdiff