systemd-ask-password - Query the user for a system password
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
•A command line agent which can be started
temporarily to process queued password requests —
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.
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.
The following options are understood:
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.
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:
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.
Specify the query timeout in seconds. Defaults to 90s. A
timeout of 0 waits indefinitely.
Echo the user input instead of masking it. This is useful
when using systemd-ask-password to query for usernames.
Never ask for password on current TTY even if one is
available. Always use agent system.
If passed, accept cached passwords, i.e. passwords
When used in conjunction with --accept-cached
accept multiple passwords. This will output one password per line.
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.
Print a short help text and exit.
On success, 0 is returned, a non-zero failure code otherwise.
- systemd Password Agent Specification
- XDG Icon Naming Specification