userdbctl(1) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | COMMANDS | WELL-KNOWN SERVICES | INTEGRATION WITH SSH | EXIT STATUS | ENVIRONMENT | SEE ALSO | NOTES | COLOPHON

USERDBCTL(1)                    userdbctl                   USERDBCTL(1)

NAME         top

       userdbctl - Inspect users, groups and group memberships

SYNOPSIS         top

       userdbctl [OPTIONS...] {COMMAND} [NAME...]

DESCRIPTION         top

       userdbctl may be used to inspect user and groups (as well as
       group memberships) of the system. This client utility inquires
       user/group information provided by various system services, both
       operating on JSON user/group records (as defined by the JSON User
       Records[1] and JSON Group Records[2] definitions), and classic
       UNIX NSS/glibc user and group records. This tool is primarily a
       client to the User/Group Record Lookup API via Varlink[3], and
       may also pick up drop-in JSON user and group records from
       /etc/userdb/, /run/userdb/, /run/host/userdb/, /usr/lib/userdb/.

OPTIONS         top

       The following options are understood:

       --output=MODE
           Choose the output mode, takes one of "classic", "friendly",
           "table", "json". If "classic", an output very close to the
           format of /etc/passwd or /etc/group is generated. If
           "friendly" a more comprehensive and user friendly, human
           readable output is generated; if "table" a minimal, tabular
           output is generated; if "json" a JSON formatted output is
           generated. Defaults to "friendly" if a user/group is
           specified on the command line, "table" otherwise.

           Note that most output formats do not show all available
           information. In particular, "classic" and "table" show only
           the most important fields. Various modes also do not show
           password hashes. Use "json" to view all fields, including any
           authentication fields.

       --service=SERVICE[:SERVICE...], -s SERVICE:SERVICE...
           Controls which services to query for users/groups. Takes a
           list of one or more service names, separated by ":". See
           below for a list of well-known service names. If not
           specified all available services are queried at once.

       --with-nss=BOOL
           Controls whether to include classic glibc/NSS user/group
           lookups in the output. If --with-nss=no is used any attempts
           to resolve or enumerate users/groups provided only via glibc
           NSS is suppressed. If --with-nss=yes is specified such
           users/groups are included in the output (which is the
           default).

       --with-varlink=BOOL
           Controls whether to include Varlink user/group lookups in the
           output, i.e. those done via the User/Group Record Lookup API
           via Varlink[3]. If --with-varlink=no is used any attempts to
           resolve or enumerate users/groups provided only via Varlink
           are suppressed. If --with-varlink=yes is specified such
           users/groups are included in the output (which is the
           default).

       --with-dropin=BOOL
           Controls whether to include user/group lookups in the output
           that are defined using drop-in files in /etc/userdb/,
           /run/userdb/, /run/host/userdb/, /usr/lib/userdb/. If
           --with-dropin=no is used these records are suppressed. If
           --with-dropin=yes is specified such users/groups are included
           in the output (which is the default).

       --synthesize=BOOL
           Controls whether to synthesize records for the root and
           nobody users/groups if they aren't defined otherwise. By
           default (or "yes") such records are implicitly synthesized if
           otherwise missing since they have special significance to the
           OS. When "no" this synthesizing is turned off.

       -N
           This option is short for --with-nss=no --synthesize=no. Use
           this option to show only records that are natively defined as
           JSON user or group records, with all NSS/glibc compatibility
           and all implicit synthesis turned off.

       --no-pager
           Do not pipe output into a pager.

       --no-legend
           Do not print the legend, i.e. column headers and the footer
           with hints.

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

       --version
           Print a short version string and exit.

COMMANDS         top

       The following commands are understood:

       user [USER...]
           List all known users records or show details of one or more
           specified user records. Use --output= to tweak output mode.

       group [GROUP...]
           List all known group records or show details of one or more
           specified group records. Use --output= to tweak output mode.

       users-in-group [GROUP...]
           List users that are members of the specified groups. If no
           groups are specified list all user/group memberships defined.
           Use --output= to tweak output mode.

       groups-of-user [USER...]
           List groups that the specified users are members of. If no
           users are specified list all user/group memberships defined
           (in this case groups-of-user and users-in-group are
           equivalent). Use --output= to tweak output mode.

       services
           List all services currently providing user/group definitions
           to the system. See below for a list of well-known services
           providing user information.

       ssh-authorized-keys
           This operation is not a public, user-facing interface. It is
           used to allow the SSH daemon to pick up authorized keys from
           user records, see below.

WELL-KNOWN SERVICES         top

       The userdbctl services command will list all currently running
       services that provide user or group definitions to the system.
       The following well-known services are shown among this list:

       io.systemd.DynamicUser
           This service is provided by the system service manager itself
           (i.e. PID 1) and makes all users (and their groups)
           synthesized through the DynamicUser= setting in service unit
           files available to the system (see systemd.exec(5) for
           details about this setting).

       io.systemd.Home
           This service is provided by systemd-homed.service(8) and
           makes all users (and their groups) belonging to home
           directories managed by that service available to the system.

       io.systemd.Machine
           This service is provided by systemd-machined.service(8) and
           synthesizes records for all users/groups used by a container
           that employs user namespacing.

       io.systemd.Multiplexer
           This service is provided by systemd-userdbd.service(8) and
           multiplexes user/group look-ups to all other running lookup
           services. This is the primary entry point for user/group
           record clients, as it simplifies client side implementation
           substantially since they can ask a single service for lookups
           instead of asking all running services in parallel.
           userdbctl uses this service preferably, too, unless
           --with-nss= or --service= are used, in which case finer
           control over the services to talk to is required.

       io.systemd.NameServiceSwitch
           This service is (also) provided by systemd-userdbd.service(8)
           and converts classic NSS/glibc user and group records to JSON
           user/group records, providing full backwards compatibility.
           Use --with-nss=no to disable this compatibility, see above.
           Note that compatibility is actually provided in both
           directions: nss-systemd(8) will automatically synthesize
           classic NSS/glibc user/group records from all JSON user/group
           records provided to the system, thus using both APIs is
           mostly equivalent and provides access to the same data,
           however the NSS/glibc APIs necessarily expose a more reduced
           set of fields only.

       io.systemd.DropIn
           This service is (also) provided by systemd-userdbd.service(8)
           and picks up JSON user/group records from /etc/userdb/,
           /run/userdb/, /run/host/userdb/, /usr/lib/userdb/.

       Note that userdbctl has internal support for NSS-based lookups
       too. This means that if neither io.systemd.Multiplexer nor
       io.systemd.NameServiceSwitch are running look-ups into the basic
       user/group databases will still work.

INTEGRATION WITH SSH         top

       The userdbctl tool may be used to make the list of SSH authorized
       keys possibly contained in a user record available to the SSH
       daemon for authentication. For that configure the following in
       sshd_config(5):

           ...
           AuthorizedKeysCommand /usr/bin/userdbctl ssh-authorized-keys %u
           AuthorizedKeysCommandUser root
           ...

EXIT STATUS         top

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

ENVIRONMENT         top

       $SYSTEMD_LOG_LEVEL
           The maximum log level of emitted messages (messages with a
           higher log level, i.e. less important ones, will be
           suppressed). Either one of (in order of decreasing
           importance) emerg, alert, crit, err, warning, notice, info,
           debug, or an integer in the range 0...7. See syslog(3) for
           more information.

       $SYSTEMD_LOG_COLOR
           A boolean. If true, messages written to the tty will be
           colored according to priority.

           This setting is only useful when messages are written
           directly to the terminal, because journalctl(1) and other
           tools that display logs will color messages based on the log
           level on their own.

       $SYSTEMD_LOG_TIME
           A boolean. If true, console log messages will be prefixed
           with a timestamp.

           This setting is only useful when messages are written
           directly to the terminal or a file, because journalctl(1) and
           other tools that display logs will attach timestamps based on
           the entry metadata on their own.

       $SYSTEMD_LOG_LOCATION
           A boolean. If true, messages will be prefixed with a filename
           and line number in the source code where the message
           originates.

           Note that the log location is often attached as metadata to
           journal entries anyway. Including it directly in the message
           text can nevertheless be convenient when debugging programs.

       $SYSTEMD_LOG_TID
           A boolean. If true, messages will be prefixed with the
           current numerical thread ID (TID).

           Note that the this information is attached as metadata to
           journal entries anyway. Including it directly in the message
           text can nevertheless be convenient when debugging programs.

       $SYSTEMD_LOG_TARGET
           The destination for log messages. One of console (log to the
           attached tty), console-prefixed (log to the attached tty but
           with prefixes encoding the log level and "facility", see
           syslog(3), kmsg (log to the kernel circular log buffer),
           journal (log to the journal), journal-or-kmsg (log to the
           journal if available, and to kmsg otherwise), auto (determine
           the appropriate log target automatically, the default), null
           (disable log output).

       $SYSTEMD_PAGER
           Pager to use when --no-pager is not given; overrides $PAGER.
           If neither $SYSTEMD_PAGER nor $PAGER are set, a set of
           well-known pager implementations are tried in turn, including
           less(1) and more(1), until one is found. If no pager
           implementation is discovered no pager is invoked. Setting
           this environment variable to an empty string or the value
           "cat" is equivalent to passing --no-pager.

       $SYSTEMD_LESS
           Override the options passed to less (by default "FRSXMK").

           Users might want to change two options in particular:

           K
               This option instructs the pager to exit immediately when
               Ctrl+C is pressed. To allow less to handle Ctrl+C itself
               to switch back to the pager command prompt, unset this
               option.

               If the value of $SYSTEMD_LESS does not include "K", and
               the pager that is invoked is less, Ctrl+C will be ignored
               by the executable, and needs to be handled by the pager.

           X
               This option instructs the pager to not send termcap
               initialization and deinitialization strings to the
               terminal. It is set by default to allow command output to
               remain visible in the terminal even after the pager
               exits. Nevertheless, this prevents some pager
               functionality from working, in particular paged output
               cannot be scrolled with the mouse.

           See less(1) for more discussion.

       $SYSTEMD_LESSCHARSET
           Override the charset passed to less (by default "utf-8", if
           the invoking terminal is determined to be UTF-8 compatible).

       $SYSTEMD_PAGERSECURE
           Takes a boolean argument. When true, the "secure" mode of the
           pager is enabled; if false, disabled. If $SYSTEMD_PAGERSECURE
           is not set at all, secure mode is enabled if the effective
           UID is not the same as the owner of the login session, see
           geteuid(2) and sd_pid_get_owner_uid(3). In secure mode,
           LESSSECURE=1 will be set when invoking the pager, and the
           pager shall disable commands that open or create new files or
           start new subprocesses. When $SYSTEMD_PAGERSECURE is not set
           at all, pagers which are not known to implement secure mode
           will not be used. (Currently only less(1) implements secure
           mode.)

           Note: when commands are invoked with elevated privileges, for
           example under sudo(8) or pkexec(1), care must be taken to
           ensure that unintended interactive features are not enabled.
           "Secure" mode for the pager may be enabled automatically as
           describe above. Setting SYSTEMD_PAGERSECURE=0 or not removing
           it from the inherited environment allows the user to invoke
           arbitrary commands. Note that if the $SYSTEMD_PAGER or $PAGER
           variables are to be honoured, $SYSTEMD_PAGERSECURE must be
           set too. It might be reasonable to completely disable the
           pager using --no-pager instead.

       $SYSTEMD_COLORS
           Takes a boolean argument. When true, systemd and related
           utilities will use colors in their output, otherwise the
           output will be monochrome. Additionally, the variable can
           take one of the following special values: "16", "256" to
           restrict the use of colors to the base 16 or 256 ANSI colors,
           respectively. This can be specified to override the automatic
           decision based on $TERM and what the console is connected to.

       $SYSTEMD_URLIFY
           The value must be a boolean. Controls whether clickable links
           should be generated in the output for terminal emulators
           supporting this. This can be specified to override the
           decision that systemd makes based on $TERM and other
           conditions.

SEE ALSO         top

       systemd(1), systemd-userdbd.service(8), systemd-homed.service(8),
       nss-systemd(8), getent(1)

NOTES         top

        1. JSON User Records
           https://systemd.io/USER_RECORD

        2. JSON Group Records
           https://systemd.io/GROUP_RECORD

        3. User/Group Record Lookup API via Varlink
           https://systemd.io/USER_GROUP_API

COLOPHON         top

       This page is part of the systemd (systemd system and service
       manager) project.  Information about the project can be found at
       ⟨http://www.freedesktop.org/wiki/Software/systemd⟩.  If you have
       a bug report for this manual page, see
       ⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
       This page was obtained from the project's upstream Git repository
       ⟨https://github.com/systemd/systemd.git⟩ on 2021-08-27.  (At that
       time, the date of the most recent commit that was found in the
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       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

systemd 249                                                 USERDBCTL(1)

Pages that refer to this page: homectl(1)systemd-homed.service(8)systemd-machined.service(8)systemd-userdbd.service(8)