xenial (1) systemd-ask-password.1.gz

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(1) message

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

       •   A TTY agent that is temporarily spawned during systemctl(1) 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(1) 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(1), systemctl(1), keyctl(1), plymouth(8), wall(1)

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