systemd-ask-password Man page

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 query the password system-wide and allow active users to
respond via several agents. The latter is only available to privileged
processes.

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

· A boot-time password agent querying the user directly on the
console

· An agent requesting password input via a wall message

· A command line agent which can be started temporarily to process
queued password requests

· A TTY agent that is temporarily spawned during systemctl
invocations

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 to access the
cached key via the kernel keyring directly. Example:
“–keyname=cryptsetup”

–timeout=
Specify the query timeout in seconds. Defaults to 90s. A timeout of
0 waits indefinitely.

–echo
Echo the user input instead of masking it. This is useful when
using systemd-ask-password to query for usernames.

–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.

-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, systemctl, keyctl, plymouth(8), wall

NOTES
1. systemd Password Agent Specification
http://www.freedesktop.org/wiki/Software/systemd/PasswordAgents

2. XDG Icon Naming Specification
http://standards.freedesktop.org/icon-naming-spec/icon-naming-spec-latest.html

systemd 229 SYSTEMD-ASK-PASSWORD(1)