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-or-later -->
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
84 the
<ulink url=
"https://systemd.io/PASSWORD_AGENTS/">systemd Password Agent
85 Specification
</ulink>.
</para>
87 <para>If a password is queried on a TTY, the user may press TAB to
88 hide the asterisks normally shown for each character typed.
89 Pressing Backspace as first key achieves the same effect.
</para>
94 <title>Options
</title>
96 <para>The following options are understood:
</para>
100 <term><option>--icon=
</option></term>
102 <listitem><para>Specify an icon name alongside the password
103 query, which may be used in all agents supporting graphical
104 display. The icon name should follow the
<ulink
105 url=
"http://standards.freedesktop.org/icon-naming-spec/icon-naming-spec-latest.html">XDG
106 Icon Naming Specification
</ulink>.
</para></listitem>
110 <term><option>--id=
</option></term>
111 <listitem><para>Specify an identifier for this password
112 query. This identifier is freely choosable and allows
113 recognition of queries by involved agents. It should include
114 the subsystem doing the query and the specific object the
115 query is done for. Example:
116 <literal>--id=cryptsetup:/dev/sda5
</literal>.
</para></listitem>
120 <term><option>--keyname=
</option></term>
121 <listitem><para>Configure a kernel keyring key name to use as
122 cache for the password. If set, then the tool will try to push
123 any collected passwords into the kernel keyring of the root
124 user, as a key of the specified name. If combined with
125 <option>--accept-cached
</option>, it will also try to retrieve
126 such cached passwords from the key in the kernel keyring
127 instead of querying the user right away. By using this option,
128 the kernel keyring may be used as effective cache to avoid
129 repeatedly asking users for passwords, if there are multiple
130 objects that may be unlocked with the same password. The
131 cached key will have a timeout of
2.5min set, after which it
132 will be purged from the kernel keyring. Note that it is
133 possible to cache multiple passwords under the same keyname,
134 in which case they will be stored as
<constant>NUL
</constant>-separated list of
136 <citerefentry project='die-net'
><refentrytitle>keyctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
137 to access the cached key via the kernel keyring
138 directly. Example:
<literal>--keyname=cryptsetup
</literal></para></listitem>
142 <term><option>--credential=
</option></term>
143 <listitem><para>Configure a credential to read the password from – if it exists. This may be used in
144 conjunction with the
<varname>LoadCredential=
</varname> and
<varname>SetCredential=
</varname>
145 settings in unit files. See
146 <citerefentry><refentrytitle>systemd.exec
</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
147 details. If not specified, defaults to
<literal>password
</literal>. This option has no effect if no
148 credentials directory is passed to the program (i.e.
<varname>$CREDENTIALS_DIRECTORY
</varname> is not
149 set) or if the no credential of the specified name exists.
</para></listitem>
153 <term><option>--timeout=
</option></term>
155 <listitem><para>Specify the query timeout in seconds. Defaults
156 to
90s. A timeout of
0 waits indefinitely.
</para></listitem>
160 <term><option>--echo
</option></term>
162 <listitem><para>Echo the user input instead of masking it.
163 This is useful when using
164 <filename>systemd-ask-password
</filename> to query for
165 usernames.
</para></listitem>
169 <term><option>--no-tty
</option></term>
171 <listitem><para>Never ask for password on current TTY even if
172 one is available. Always use agent system.
</para></listitem>
176 <term><option>--accept-cached
</option></term>
178 <listitem><para>If passed, accept cached passwords, i.e.
179 passwords previously entered.
</para></listitem>
183 <term><option>--multiple
</option></term>
185 <listitem><para>When used in conjunction with
186 <option>--accept-cached
</option> accept multiple passwords.
187 This will output one password per line.
</para></listitem>
191 <term><option>--no-output
</option></term>
193 <listitem><para>Do not print passwords to standard output.
194 This is useful if you want to store a password in kernel
195 keyring with
<option>--keyname
</option> but do not want it
196 to show up on screen or in logs.
</para></listitem>
199 <xi:include href=
"standard-options.xml" xpointer=
"help" />
205 <title>Exit status
</title>
207 <para>On success,
0 is returned, a non-zero failure code
212 <title>See Also
</title>
214 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
215 <citerefentry><refentrytitle>systemd-ask-password-console.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
216 <citerefentry><refentrytitle>systemd-tty-ask-password-agent
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
217 <citerefentry project='die-net'
><refentrytitle>keyctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
218 <citerefentry project='die-net'
><refentrytitle>plymouth
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
219 <citerefentry project='man-pages'
><refentrytitle>wall
</refentrytitle><manvolnum>1</manvolnum></citerefentry>