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  • Committer: Björn Påhlsson
  • Date: 2008-08-08 01:51:58 UTC
  • mto: (237.7.1 mandos) (24.1.154 mandos)
  • mto: This revision was merged to the branch mainline in revision 50.
  • Revision ID: belorn@braxen-20080808015158-gudud63aet3l8jlw
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plugins.d/usplash.xml
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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        "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
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<!ENTITY COMMANDNAME "usplash">
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<!ENTITY TIMESTAMP "2017-02-23">
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<!ENTITY % common SYSTEM "../common.ent">
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%common;
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]>
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<refentry xmlns:xi="http://www.w3.org/2001/XInclude">
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  <refentryinfo>
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    <title>Mandos Manual</title>
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    <!-- NWalsh’s docbook scripts use this to generate the footer: -->
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    <productname>Mandos</productname>
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    <productnumber>&version;</productnumber>
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    <date>&TIMESTAMP;</date>
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    <authorgroup>
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      <author>
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        <firstname>Björn</firstname>
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        <surname>Påhlsson</surname>
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        <address>
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          <email>belorn@recompile.se</email>
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        </address>
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      </author>
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      <author>
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        <firstname>Teddy</firstname>
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        <surname>Hogeborn</surname>
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        <address>
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          <email>teddy@recompile.se</email>
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        </address>
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      </author>
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    </authorgroup>
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    <copyright>
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      <year>2008</year>
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      <year>2009</year>
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      <year>2010</year>
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      <year>2011</year>
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      <year>2012</year>
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      <year>2013</year>
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      <year>2014</year>
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      <year>2015</year>
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      <year>2016</year>
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      <year>2017</year>
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      <holder>Teddy Hogeborn</holder>
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      <holder>Björn Påhlsson</holder>
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    </copyright>
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    <xi:include href="../legalnotice.xml"/>
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  </refentryinfo>
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  <refmeta>
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    <refentrytitle>&COMMANDNAME;</refentrytitle>
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    <manvolnum>8mandos</manvolnum>
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  </refmeta>
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  <refnamediv>
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    <refname><command>&COMMANDNAME;</command></refname>
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    <refpurpose>Mandos plugin to use usplash to get a
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    password.</refpurpose>
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  </refnamediv>
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  <refsynopsisdiv>
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    <cmdsynopsis>
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      <command>&COMMANDNAME;</command>
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    </cmdsynopsis>
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  </refsynopsisdiv>
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  <refsect1 id="description">
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    <title>DESCRIPTION</title>
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    <para>
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      This program prompts for a password using <citerefentry>
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      <refentrytitle>usplash</refentrytitle><manvolnum>8</manvolnum>
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      </citerefentry> and outputs any given password to standard
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      output.  If no <citerefentry><refentrytitle
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      >usplash</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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      process can be found, this program will immediately exit with an
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      exit code indicating failure.
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    </para>
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    <para>
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      This program is not very useful on its own.  This program is
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      really meant to run as a plugin in the <application
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      >Mandos</application> client-side system, where it is used as a
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      fallback and alternative to retrieving passwords from a
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      <application >Mandos</application> server.
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    </para>
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    <para>
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      If this program is killed (presumably by
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      <citerefentry><refentrytitle>plugin-runner</refentrytitle>
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      <manvolnum>8mandos</manvolnum></citerefentry> because some other
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      plugin provided the password), it cannot tell <citerefentry>
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      <refentrytitle>usplash</refentrytitle><manvolnum>8</manvolnum>
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      </citerefentry> to abort requesting a password, because
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      <citerefentry><refentrytitle>usplash</refentrytitle>
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      <manvolnum>8</manvolnum></citerefentry> does not support this.
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      Therefore, this program will then <emphasis>kill</emphasis> the
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      running <citerefentry><refentrytitle>usplash</refentrytitle>
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      <manvolnum>8</manvolnum></citerefentry> process and start a
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      <emphasis>new</emphasis> one using the same command line
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      arguments as the old one was using.
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    </para>
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  </refsect1>
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  <refsect1 id="options">
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    <title>OPTIONS</title>
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    <para>
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      This program takes no options.
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    </para>
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  </refsect1>
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  <refsect1 id="exit_status">
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    <title>EXIT STATUS</title>
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    <para>
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      If exit status is 0, the output from the program is the password
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      as it was read.  Otherwise, if exit status is other than 0, the
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      program was interrupted or encountered an error, and any output
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      so far could be corrupt and/or truncated, and should therefore
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      be ignored.
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    </para>
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  </refsect1>
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  <refsect1 id="environment">
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    <title>ENVIRONMENT</title>
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    <variablelist>
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      <varlistentry>
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        <term><envar>cryptsource</envar></term>
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        <term><envar>crypttarget</envar></term>
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        <listitem>
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          <para>
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            If set, these environment variables will be assumed to
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            contain the source device name and the target device
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            mapper name, respectively, and will be shown as part of
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            the prompt.
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        </para>
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        <para>
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          These variables will normally be inherited from
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          <citerefentry><refentrytitle>plugin-runner</refentrytitle>
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          <manvolnum>8mandos</manvolnum></citerefentry>, which will
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          normally have inherited them from
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          <filename>/scripts/local-top/cryptroot</filename> in the
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          initial <acronym>RAM</acronym> disk environment, which will
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          have set them from parsing kernel arguments and
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          <filename>/conf/conf.d/cryptroot</filename> (also in the
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          initial RAM disk environment), which in turn will have been
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          created when the initial RAM disk image was created by
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          <filename
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          >/usr/share/initramfs-tools/hooks/cryptroot</filename>, by
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          extracting the information of the root file system from
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          <filename >/etc/crypttab</filename>.
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        </para>
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        <para>
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          This behavior is meant to exactly mirror the behavior of
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          <command>askpass</command>, the default password prompter.
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        </para>
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        </listitem>
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      </varlistentry>
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    </variablelist>
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  </refsect1>
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  <refsect1 id="files">
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    <title>FILES</title>
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    <variablelist>
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      <varlistentry>
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        <term><filename>/dev/.initramfs/usplash_fifo</filename></term>
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        <listitem>
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          <para>
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            This is the <acronym>FIFO</acronym> to where this program
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            will write the commands for <citerefentry><refentrytitle
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            >usplash</refentrytitle><manvolnum>8</manvolnum>
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            </citerefentry>.  See <citerefentry><refentrytitle
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            >fifo</refentrytitle><manvolnum>7</manvolnum>
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            </citerefentry>.
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          </para>
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        </listitem>
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      </varlistentry>
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      <varlistentry>
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        <term><filename>/dev/.initramfs/usplash_outfifo</filename></term>
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        <listitem>
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          <para>
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            This is the <acronym>FIFO</acronym> where this program
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            will read the password from <citerefentry><refentrytitle
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            >usplash</refentrytitle><manvolnum>8</manvolnum>
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            </citerefentry>.  See <citerefentry><refentrytitle
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            >fifo</refentrytitle><manvolnum>7</manvolnum>
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            </citerefentry>.
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          </para>
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        </listitem>
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      </varlistentry>
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      <varlistentry>
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        <term><filename class="directory">/proc</filename></term>
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        <listitem>
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          <para>
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            To find the running <citerefentry><refentrytitle
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            >usplash</refentrytitle><manvolnum>8</manvolnum>
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            </citerefentry>, this directory will be searched for
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            numeric entries which will be assumed to be directories.
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            In all those directories, the <filename>exe</filename> and
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            <filename>cmdline</filename> entries will be used to
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            determine the name of the running binary, effective user
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            and group <abbrev>ID</abbrev>, and the command line
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            arguments.  See <citerefentry><refentrytitle
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            >proc</refentrytitle><manvolnum>5</manvolnum>
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            </citerefentry>.
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          </para>
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        </listitem>
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      </varlistentry>
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      <varlistentry>
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        <term><filename>/sbin/usplash</filename></term>
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        <listitem>
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          <para>
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            This is the name of the binary which will be searched for
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            in the process list.  See <citerefentry><refentrytitle
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            >usplash</refentrytitle><manvolnum>8</manvolnum>
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            </citerefentry>.
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          </para>
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        </listitem>
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      </varlistentry>
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    </variablelist>
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  </refsect1>
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  <refsect1 id="bugs">
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    <title>BUGS</title>
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    <para>
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      Killing <citerefentry><refentrytitle>usplash</refentrytitle>
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      <manvolnum>8</manvolnum></citerefentry> and starting a new one
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      is ugly, but necessary as long as it does not support aborting a
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      password request.
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    </para>
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    <xi:include href="../bugs.xml"/>
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  </refsect1>
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  <refsect1 id="example">
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    <title>EXAMPLE</title>
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    <para>
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      Note that normally, this program will not be invoked directly,
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      but instead started by the Mandos <citerefentry><refentrytitle
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      >plugin-runner</refentrytitle><manvolnum>8mandos</manvolnum>
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      </citerefentry>.
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    </para>
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    <informalexample>
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      <para>
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        This program takes no options.
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      </para>
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      <para>
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        <userinput>&COMMANDNAME;</userinput>
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      </para>
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    </informalexample>
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  </refsect1>
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  <refsect1 id="security">
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    <title>SECURITY</title>
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    <para>
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      If this program is killed by a signal, it will kill the process
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      <abbrev>ID</abbrev> which at the start of this program was
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      determined to run <citerefentry><refentrytitle
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      >usplash</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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      as root (see also <xref linkend="files"/>).  There is a very
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      slight risk that, in the time between those events, that process
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      <abbrev>ID</abbrev> was freed and then taken up by another
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      process; the wrong process would then be killed.  Now, this
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      program can only be killed by the user who started it; see
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      <citerefentry><refentrytitle>plugin-runner</refentrytitle>
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      <manvolnum>8mandos</manvolnum></citerefentry>.  This program
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      should therefore be started by a completely separate
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      non-privileged user, and no other programs should be allowed to
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      run as that special user.  This means that it is not recommended
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      to use the user "nobody" to start this program, as other
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      possibly less trusted programs could be running as "nobody", and
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      they would then be able to kill this program, triggering the
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      killing of the process <abbrev>ID</abbrev> which may or may not
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      be <citerefentry><refentrytitle>usplash</refentrytitle>
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      <manvolnum>8</manvolnum></citerefentry>.
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    </para>
272
 
    <para>
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      The only other thing that could be considered worthy of note is
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      this:  This program is meant to be run by <citerefentry>
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      <refentrytitle>plugin-runner</refentrytitle><manvolnum
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      >8mandos</manvolnum></citerefentry>, and will, when run
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      standalone, outside, in a normal environment, immediately output
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      on its standard output any presumably secret password it just
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      received.  Therefore, when running this program standalone
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      (which should never normally be done), take care not to type in
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      any real secret password by force of habit, since it would then
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      immediately be shown as output.
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    </para>
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  </refsect1>
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  <refsect1 id="see_also">
287
 
    <title>SEE ALSO</title>
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    <para>
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      <citerefentry><refentrytitle>intro</refentrytitle>
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      <manvolnum>8mandos</manvolnum></citerefentry>,
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      <citerefentry><refentrytitle>crypttab</refentrytitle>
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      <manvolnum>5</manvolnum></citerefentry>,
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      <citerefentry><refentrytitle>fifo</refentrytitle>
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      <manvolnum>7</manvolnum></citerefentry>,
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      <citerefentry><refentrytitle>plugin-runner</refentrytitle>
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      <manvolnum>8mandos</manvolnum></citerefentry>,
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      <citerefentry><refentrytitle>proc</refentrytitle>
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      <manvolnum>5</manvolnum></citerefentry>,
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      <citerefentry><refentrytitle>usplash</refentrytitle>
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      <manvolnum>8</manvolnum></citerefentry>
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    </para>
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  </refsect1>
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</refentry>
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<!-- Local Variables: -->
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<!-- time-stamp-start: "<!ENTITY TIMESTAMP [\"']" -->
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<!-- time-stamp-end: "[\"']>" -->
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<!-- time-stamp-format: "%:y-%02m-%02d" -->
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<!-- End: -->