systemd-ask-password

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:

       o   A boot-time password agent asking the user for passwords using
           plymouth(8),

       o   A boot-time password agent querying the user directly on the
           console -- systemd-ask-password-console.service(8),

       o   An agent requesting password input via a wall(1) message --
           systemd-ask-password-wall.service(8),

       o   A TTY agent that is temporarily spawned during systemctl(1)
           invocations,

       o   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 writing the acquired password to standard output
           it is suffixed by a newline character. This may be turned off with
           the -n switch, similar 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
           http://standards.freedesktop.org/icon-naming-spec/icon-naming-spec-latest.html

systemd 249                                            SYSTEMD-ASK-PASSWORD(1)