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<?xml version='1.0'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="systemd-ask-password"
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>systemd-ask-password</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>systemd-ask-password</refentrytitle>
<manvolnum>1</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd-ask-password</refname>
<refpurpose>Query the user for a system password</refpurpose>
</refnamediv>
<refsynopsisdiv>
<cmdsynopsis>
<command>systemd-ask-password <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="opt">MESSAGE</arg></command>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><command>systemd-ask-password</command> may be used to query
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 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.
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>
<para>Existing agents are:
<itemizedlist>
<listitem><para>A boot-time password agent asking the user for
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 —
<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 —
<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>
<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="https://systemd.io/PASSWORD_AGENTS/">systemd Password Agent
Specification</ulink>.</para>
<para>If a password is queried on a TTY, the user may press TAB to
hide the asterisks normally shown for each character typed.
Pressing Backspace as first key achieves the same effect.</para>
</refsect1>
<refsect1>
<title>Options</title>
<para>The following options are understood:</para>
<variablelist>
<varlistentry>
<term><option>--icon=</option></term>
<listitem><para>Specify an icon name alongside the password
query, which may be used in all agents supporting graphical
display. The icon name should follow the <ulink
url="http://standards.freedesktop.org/icon-naming-spec/icon-naming-spec-latest.html">XDG
Icon Naming Specification</ulink>.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--id=</option></term>
<listitem><para>Specify an identifier for this password
query. This identifier is freely choosable and allows
recognition of queries by involved agents. It should include
the subsystem doing the query and the specific object the
query is done for. Example:
<literal>--id=cryptsetup:/dev/sda5</literal>.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--keyname=</option></term>
<listitem><para>Configure a kernel keyring key name to use as
cache for the password. If set, then the tool will try to push
any collected passwords into the kernel keyring of the root
user, as a key of the specified name. If combined with
<option>--accept-cached</option>, it will also try to retrieve
such cached passwords from the key in the kernel keyring
instead of querying the user right away. By using this option,
the kernel keyring may be used as effective cache to avoid
repeatedly asking users for passwords, if there are multiple
objects that may be unlocked with the same password. The
cached key will have a timeout of 2.5min set, after which it
will be purged from the kernel keyring. Note that it is
possible to cache multiple passwords under the same keyname,
in which case they will be stored as <constant>NUL</constant>-separated list of
passwords. Use
<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>
<varlistentry>
<term><option>--timeout=</option></term>
<listitem><para>Specify the query timeout in seconds. Defaults
to 90s. A timeout of 0 waits indefinitely. </para></listitem>
</varlistentry>
<varlistentry>
<term><option>--echo</option></term>
<listitem><para>Echo the user input instead of masking it.
This is useful when using
<filename>systemd-ask-password</filename> to query for
usernames. </para></listitem>
</varlistentry>
<varlistentry>
<term><option>--no-tty</option></term>
<listitem><para>Never ask for password on current TTY even if
one is available. Always use agent system.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--accept-cached</option></term>
<listitem><para>If passed, accept cached passwords, i.e.
passwords previously entered.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--multiple</option></term>
<listitem><para>When used in conjunction with
<option>--accept-cached</option> accept multiple passwords.
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>
</refsect1>
<refsect1>
<title>Exit status</title>
<para>On success, 0 is returned, a non-zero failure code
otherwise.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</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>
</refsect1>
</refentry>
|
