systemd-ask-password(1) — Linux manual page


SYSTEMD-ASK-PASSWORD(1)   systemd-ask-password   SYSTEMD-ASK-PASSWORD(1)

NAME         top

       systemd-ask-password - Query the user for a system password

SYNOPSIS         top

       systemd-ask-password [OPTIONS...] [MESSAGE]

DESCRIPTION         top

       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 —

       •   A TTY agent that is temporarily spawned during systemctl(1)

       •   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         top

       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[2].

           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".

           Added in version 227.

           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"

           Added in version 227.

           Configure a credential to read the password from – if it
           exists. This may be used in conjunction with the
           ImportCredential=, 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.

           Added in version 249.

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

           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).

           Added in version 249.

       --echo, -e
           Equivalent to --echo=yes, see above.

           Added in version 217.

           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

           Added in version 249.

           Never ask for password on current TTY even if one is
           available. Always use agent system.

           If passed, accept cached passwords, i.e. passwords previously

           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

           Added in version 230.

           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.

           Added in version 249.

       -h, --help
           Print a short help text and exit.

EXIT STATUS         top

       On success, 0 is returned, a non-zero failure code otherwise.

SEE ALSO         top

       systemd(1), systemd-ask-password-console.service(8),
       systemd-tty-ask-password-agent(1), keyctl(1), plymouth(8),

NOTES         top

        1. systemd Password Agent Specification

        2. XDG Icon Naming Specification

COLOPHON         top

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       This page was obtained from the project's upstream Git repository
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systemd 257~devel                                SYSTEMD-ASK-PASSWORD(1)

Pages that refer to this page: systemd-tty-ask-password-agent(1)systemd.directives(7)systemd.index(7)pam_systemd_loadkey(8)