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 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.
NOTES¶
- 1.
- systemd Password Agent Specification
- 2.
- XDG Icon Naming Specification
