2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
6 <refentry id=
"systemd-ask-password"
7 xmlns:
xi=
"http://www.w3.org/2001/XInclude">
10 <title>systemd-ask-password
</title>
11 <productname>systemd
</productname>
15 <refentrytitle>systemd-ask-password
</refentrytitle>
16 <manvolnum>1</manvolnum>
20 <refname>systemd-ask-password
</refname>
21 <refpurpose>Query the user for a system password
</refpurpose>
26 <command>systemd-ask-password
<arg choice=
"opt" rep=
"repeat">OPTIONS
</arg> <arg choice=
"opt">MESSAGE
</arg></command>
31 <title>Description
</title>
33 <para><command>systemd-ask-password
</command> may be used to query
34 a system password or passphrase from the user, using a question
35 message specified on the command line. When run from a TTY it will
36 query a password on the TTY and print it to standard output. When
37 run with no TTY or with
<option>--no-tty
</option> it will use the
38 system-wide query mechanism, which allows active users to respond via
39 several agents, listed below.
</para>
41 <para>The purpose of this tool is to query system-wide passwords
42 — that is passwords not attached to a specific user account.
43 Examples include: unlocking encrypted hard disks when they are
44 plugged in or at boot, entering an SSL certificate passphrase for
45 web and VPN servers.
</para>
47 <para>Existing agents are:
50 <listitem><para>A boot-time password agent asking the user for
52 <citerefentry project='die-net'
><refentrytitle>plymouth
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
55 <listitem><para>A boot-time password agent querying the user
56 directly on the console —
57 <citerefentry><refentrytitle>systemd-ask-password-console.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
60 <listitem><para>An agent requesting password input via a
61 <citerefentry project='man-pages'
><refentrytitle>wall
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
63 <citerefentry><refentrytitle>systemd-ask-password-wall.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
66 <listitem><para>A TTY agent that is temporarily spawned during
67 <citerefentry><refentrytitle>systemctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
68 invocations,
</para></listitem>
70 <listitem><para>A command line agent which can be started
71 temporarily to process queued password
72 requests —
<command>systemd-tty-ask-password-agent --query
</command>.
74 </itemizedlist></para>
76 <para>Answering system-wide password queries is a privileged operation, hence
77 all the agents listed above (except for the last one), run as privileged
78 system services. The last one also needs elevated privileges, so
80 <citerefentry project='die-net'
><refentrytitle>sudo
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
83 <para>Additional password agents may be implemented according to
85 url=
"https://www.freedesktop.org/wiki/Software/systemd/PasswordAgents">systemd
86 Password Agent Specification
</ulink>.
</para>
88 <para>If a password is queried on a TTY, the user may press TAB to
89 hide the asterisks normally shown for each character typed.
90 Pressing Backspace as first key achieves the same effect.
</para>
95 <title>Options
</title>
97 <para>The following options are understood:
</para>
101 <term><option>--icon=
</option></term>
103 <listitem><para>Specify an icon name alongside the password
104 query, which may be used in all agents supporting graphical
105 display. The icon name should follow the
<ulink
106 url=
"http://standards.freedesktop.org/icon-naming-spec/icon-naming-spec-latest.html">XDG
107 Icon Naming Specification
</ulink>.
</para></listitem>
111 <term><option>--id=
</option></term>
112 <listitem><para>Specify an identifier for this password
113 query. This identifier is freely choosable and allows
114 recognition of queries by involved agents. It should include
115 the subsystem doing the query and the specific object the
116 query is done for. Example:
117 <literal>--id=cryptsetup:/dev/sda5
</literal>.
</para></listitem>
121 <term><option>--keyname=
</option></term>
122 <listitem><para>Configure a kernel keyring key name to use as
123 cache for the password. If set, then the tool will try to push
124 any collected passwords into the kernel keyring of the root
125 user, as a key of the specified name. If combined with
126 <option>--accept-cached
</option>, it will also try to retrieve
127 such cached passwords from the key in the kernel keyring
128 instead of querying the user right away. By using this option,
129 the kernel keyring may be used as effective cache to avoid
130 repeatedly asking users for passwords, if there are multiple
131 objects that may be unlocked with the same password. The
132 cached key will have a timeout of
2.5min set, after which it
133 will be purged from the kernel keyring. Note that it is
134 possible to cache multiple passwords under the same keyname,
135 in which case they will be stored as NUL-separated list of
137 <citerefentry project='die-net'
><refentrytitle>keyctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
138 to access the cached key via the kernel keyring
139 directly. Example:
<literal>--keyname=cryptsetup
</literal></para></listitem>
143 <term><option>--timeout=
</option></term>
145 <listitem><para>Specify the query timeout in seconds. Defaults
146 to
90s. A timeout of
0 waits indefinitely.
</para></listitem>
150 <term><option>--echo
</option></term>
152 <listitem><para>Echo the user input instead of masking it.
153 This is useful when using
154 <filename>systemd-ask-password
</filename> to query for
155 usernames.
</para></listitem>
159 <term><option>--no-tty
</option></term>
161 <listitem><para>Never ask for password on current TTY even if
162 one is available. Always use agent system.
</para></listitem>
166 <term><option>--accept-cached
</option></term>
168 <listitem><para>If passed, accept cached passwords, i.e.
169 passwords previously entered.
</para></listitem>
173 <term><option>--multiple
</option></term>
175 <listitem><para>When used in conjunction with
176 <option>--accept-cached
</option> accept multiple passwords.
177 This will output one password per line.
</para></listitem>
181 <term><option>--no-output
</option></term>
183 <listitem><para>Do not print passwords to standard output.
184 This is useful if you want to store a password in kernel
185 keyring with
<option>--keyname
</option> but do not want it
186 to show up on screen or in logs.
</para></listitem>
189 <xi:include href=
"standard-options.xml" xpointer=
"help" />
195 <title>Exit status
</title>
197 <para>On success,
0 is returned, a non-zero failure code
202 <title>See Also
</title>
204 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
205 <citerefentry><refentrytitle>systemd-ask-password-console.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
206 <citerefentry><refentrytitle>systemd-tty-ask-password-agent
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
207 <citerefentry project='die-net'
><refentrytitle>keyctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
208 <citerefentry project='die-net'
><refentrytitle>plymouth
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
209 <citerefentry project='man-pages'
><refentrytitle>wall
</refentrytitle><manvolnum>1</manvolnum></citerefentry>