"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
+ SPDX-License-Identifier: LGPL-2.1+
+
This file is part of systemd.
Copyright 2011 Lennart Poettering
a system password or passphrase from the user, using a question
message specified on the command line. When run from a TTY it will
query a password on the TTY and print it to standard output. When
- run with no TTY or with <option>--no-tty</option> it will query
- the password system-wide and allow active users to respond via
- several agents. The latter is only available to privileged
- processes.</para>
+ run with no TTY or with <option>--no-tty</option> it will use the
+ system-wide query mechanism, which allows active users to respond via
+ several agents, listed below.</para>
<para>The purpose of this tool is to query system-wide passwords
- -- that is passwords not attached to a specific user account.
+ — that is passwords not attached to a specific user account.
Examples include: unlocking encrypted hard disks when they are
plugged in or at boot, entering an SSL certificate passphrase for
web and VPN servers.</para>
<itemizedlist>
<listitem><para>A boot-time password agent asking the user for
- passwords using Plymouth</para></listitem>
+ passwords using
+ <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+ </para></listitem>
<listitem><para>A boot-time password agent querying the user
- directly on the console</para></listitem>
+ directly on the console —
+ <citerefentry><refentrytitle>systemd-ask-password-console.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+ </para></listitem>
<listitem><para>An agent requesting password input via a
- <citerefentry
- project='man-pages'><refentrytitle>wall</refentrytitle><manvolnum>1</manvolnum></citerefentry>
- message</para></listitem>
-
- <listitem><para>A command line agent which can be started
- temporarily to process queued password
- requests</para></listitem>
+ <citerefentry project='man-pages'><refentrytitle>wall</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ message —
+ <citerefentry><refentrytitle>systemd-ask-password-wall.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+ </para></listitem>
<listitem><para>A TTY agent that is temporarily spawned during
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
- invocations</para></listitem>
+ invocations,</para></listitem>
+
+ <listitem><para>A command line agent which can be started
+ temporarily to process queued password
+ requests — <command>systemd-tty-ask-password-agent --query</command>.
+ </para></listitem>
</itemizedlist></para>
+ <para>Answering system-wide password queries is a privileged operation, hence
+ all the agents listed above (except for the last one), run as privileged
+ system services. The last one also needs elevated privileges, so
+ should be run through
+ <citerefentry project='die-net'><refentrytitle>sudo</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ or similar.</para>
+
<para>Additional password agents may be implemented according to
the <ulink
- url="http://www.freedesktop.org/wiki/Software/systemd/PasswordAgents">systemd
+ url="https://www.freedesktop.org/wiki/Software/systemd/PasswordAgents">systemd
Password Agent Specification</ulink>.</para>
<para>If a password is queried on a TTY, the user may press TAB to
possible to cache multiple passwords under the same keyname,
in which case they will be stored as NUL-separated list of
passwords. Use
- <citerefentry><refentrytitle>keyctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ <citerefentry project='die-net'><refentrytitle>keyctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
to access the cached key via the kernel keyring
directly. Example: <literal>--keyname=cryptsetup</literal></para></listitem>
</varlistentry>
This will output one password per line.</para></listitem>
</varlistentry>
+ <varlistentry>
+ <term><option>--no-output</option></term>
+
+ <listitem><para>Do not print passwords to standard output.
+ This is useful if you want to store a password in kernel
+ keyring with <option>--keyname</option> but do not want it
+ to show up on screen or in logs.</para></listitem>
+ </varlistentry>
+
<xi:include href="standard-options.xml" xpointer="help" />
</variablelist>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>keyctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd-ask-password-console.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd-tty-ask-password-agent</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry project='die-net'><refentrytitle>keyctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>wall</refentrytitle><manvolnum>1</manvolnum></citerefentry>
</para>
projects / thirdparty / systemd.git / blobdiff