SYSTEMD-ASK-PASSWORD(1) systemd-ask-password SYSTEMD-ASK-PASSWORD(1)
NAME
systemd-ask-password - Query the user for a system password
SYNOPSIS
systemd-ask-password [OPTIONS...] [MESSAGE]
DESCRIPTION
systemd-ask-password 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 --no-tty
it will use the system-wide query mechanism, which allows active users
to respond via several agents, listed below.
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.
Existing agents are:
• A boot-time password agent asking the user for passwords using
plymouth(8),
• A boot-time password agent querying the user directly on the
console — systemd-ask-password-console.service(8),
• An agent requesting password input via a wall(1) message — systemd-
ask-password-wall.service(8),
• A TTY agent that is temporarily spawned during systemctl(1)
invocations,
• A command line agent which can be started temporarily to process
queued password requests — systemd-tty-ask-password-agent --query.
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 sudo(8) or similar.
Additional password agents may be implemented according to the systemd
Password Agent Specification[1].
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.
OPTIONS
The following options are understood:
--icon=
Specify an icon name alongside the password query, which may be
used in all agents supporting graphical display. The icon name
should follow the XDG Icon Naming Specification[2].
--id=
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:
"--id=cryptsetup:/dev/sda5".
--keyname=
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 --accept-cached, 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 NUL-separated list of passwords. Use keyctl(1) to access the
cached key via the kernel keyring directly. Example:
"--keyname=cryptsetup"
--credential=
Configure a credential to read the password from – if it exists.
This may be used in conjunction with the LoadCredential= and
SetCredential= settings in unit files. See systemd.exec(5) for
details. If not specified, defaults to "password". This option has
no effect if no credentials directory is passed to the program
(i.e. $CREDENTIALS_DIRECTORY is not set) or if the no credential
of the specified name exists.
--timeout=
Specify the query timeout in seconds. Defaults to 90s. A timeout of
0 waits indefinitely.
--echo=yes|no|masked
Controls whether to echo user input. Takes a boolean or the special
string "masked", the default being the latter. If enabled the typed
characters are echoed literally, which is useful for prompting for
usernames and other non-protected data. If disabled the typed
characters are not echoed in any form, the user will not get
feedback on their input. If set to "masked", an asterisk ("*") is
echoed for each character typed. In this mode, if the user hits the
tabulator key ("↹"), echo is turned off. (Alternatively, if the
user hits the backspace key ("⌫") while no data has been entered
otherwise, echo is turned off, too).
--echo, -e
Equivalent to --echo=yes, see above.
--emoji=yes|no|auto
Controls whether or not to prefix the query with a lock and key
emoji (🔐), if the TTY settings permit this. The default is "auto",
which defaults to "yes", unless --echo=yes is given.
--no-tty
Never ask for password on current TTY even if one is available.
Always use agent system.
--accept-cached
If passed, accept cached passwords, i.e. passwords previously
entered.
--multiple
When used in conjunction with --accept-cached accept multiple
passwords. This will output one password per line.
--no-output
Do not print passwords to standard output. This is useful if you
want to store a password in kernel keyring with --keyname= but do
not want it to show up on screen or in logs.
-n
By default, when the acquired password is written to standard
output it is suffixed by a newline character. This may be turned
off with the -n switch, similarly to the switch of the same name of
the echo(1) command.
-h, --help
Print a short help text and exit.
EXIT STATUS
On success, 0 is returned, a non-zero failure code otherwise.
SEE ALSO
systemd(1), systemd-ask-password-console.service(8), systemd-tty-ask-
password-agent(1), keyctl(1), plymouth(8), wall(1)
NOTES
1. systemd Password Agent Specification
https://systemd.io/PASSWORD_AGENTS/
2. XDG Icon Naming Specification
https://standards.freedesktop.org/icon-naming-spec/icon-naming-spec-latest.html
systemd 252 SYSTEMD-ASK-PASSWORD(1)
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