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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | COMMANDS | WELL-KNOWN SERVICES | INTEGRATION WITH SSH | EXIT STATUS | ENVIRONMENT | SEE ALSO | NOTES | COLOPHON |
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USERDBCTL(1) userdbctl USERDBCTL(1)
userdbctl - Inspect users, groups and group memberships
userdbctl [OPTIONS...] {COMMAND} [NAME...]
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/
(see nss-systemd(8) for details about drop-in user records).
The following options are understood:
--output=MODE
Chooses the output mode. Takes one of "classic", "friendly",
"table" or "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.
Added in version 245.
--json=FORMAT
Selects JSON output mode (like --output=json) and selects the
precise display mode. Takes one of "pretty" or "short". If
"pretty", human-friendly whitespace and newlines are inserted
in the output to make the JSON data more readable. If "short",
all superfluous whitespace is suppressed.
Added in version 250.
--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.
Added in version 245.
--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).
Added in version 245.
--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).
Added in version 249.
--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).
Added in version 249.
--synthesize=BOOL
Controls whether to synthesize records for the root and nobody
users/groups if they are not defined otherwise, as well as the
user/groups for the "foreign" UID range. By default (or with
"yes"), such records are implicitly synthesized if otherwise
missing since they have special significance to the OS. When
"no", this synthesizing is turned off.
Added in version 245.
-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.
Added in version 245.
--multiplexer=BOOL
Controls whether to do lookups via the multiplexer service (if
specified as true, the default) or do lookups in the client
(if specified as false). Using the multiplexer service is
typically preferable, since it runs in a locked down sandbox.
Added in version 250.
--chain
When used with the ssh-authorized-keys command, this will
allow passing an additional command line after the user name
that is chain executed after the lookup completed. This allows
chaining multiple tools that show SSH authorized keys.
Added in version 250.
--fuzzy, -z
When used with the user or group command, do a fuzzy string
search. Any specified arguments will be matched against the
user name, the real name of the user record, the email
address, and other descriptive strings of the user or group
record. Moreover, instead of precise matching, a substring
match or a match allowing slight deviations in spelling is
applied.
Added in version 257.
--disposition=
When used with the user or group command, filters by
disposition of the record. Takes one of "intrinsic", "system",
"regular", "dynamic", "container". May be used multiple times,
in which case only users matching any of the specified
dispositions are shown.
Added in version 257.
-I, -S, -R
Shortcuts for --disposition=intrinsic, --disposition=system,
--disposition=regular, respectively.
Added in version 257.
--uid-min=, --uid-max=
When used with the user or group command, filters the output
by UID/GID ranges. Takes numeric minimum or maximum UID/GID
values, respectively. Shows only records within the specified
range. When applied to the user command, it matches against
UIDs. When applied to the group command, matches against GIDs
(despite the name of the switch). If unspecified, defaults to
0 (for the minimum) and 4294967294 (for the maximum), i.e. by
default, no filtering is applied, as the whole UID/GID range
is covered.
Added in version 257.
--boundaries=
When used with the user or group command, controls whether to
show relevant UID/GID range boundary information in the
tabular output. Takes a boolean. Defaults to true.
Added in version 257.
-B
Shortcut for --boundaries=no.
Added in version 257.
--from-file=PATH, -f
When used with the user or group command, read the user
definition in JSON format from the specified file, instead of
querying it from the system. If the path is specified as "-",
reads the JSON data from standard input. This is useful to
validate and introspect JSON user or group records quickly,
and check how they would be interpreted on the local system.
Added in version 258.
--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.
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.
If used in conjunction with --from-file= the user record data
is read in JSON format from the specified file instead of
querying it from the system. For details see above.
Added in version 245.
group [GROUP...]
List all known group records or show details of one or more
specified group records. Use --output= to tweak the output
mode.
If used in conjunction with --from-file= the group record data
is read in JSON format from the specified file instead of
querying it from the system. For details see above.
Added in version 245.
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 the output mode.
Added in version 245.
groups-of-user [USER...]
Lists groups that the specified users are members of. If no
users are specified, lists all user/group memberships defined
(in this case, groups-of-user and users-in-group are
equivalent). Use --output= to tweak the output mode.
Added in version 245.
services
List all services currently providing user/group definitions
to the system. See below for a list of well-known services
providing user information.
Added in version 245.
ssh-authorized-keys
Show SSH authorized keys for this account. This command is
intended to be used to allow the SSH daemon to pick up
authorized keys from user records, see below.
Added in version 245.
load-credentials
When specified, the following credentials are used when passed
in:
userdb.user.*, userdb.group.*
These credentials should contain valid JSON User[1] and
JSON Group[2] records. For each matching credential,
various files are created in /etc/userdb/, implementing
the interface described in nss-systemd(8). Any passed user
records must contain valid UID and GID fields. Any passed
group records must contain a GID field (i.e. automatic
UID/GID allocation is not supported). For both user and
group records, the credential suffix (for
"userdb.user.foobar" the suffix is "foobar") must match
the user or group name encoded in the record.
Added in version 258.
Added in version 258.
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).
Added in version 245.
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.
Added in version 245.
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.
Added in version 246.
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.
Added in version 245.
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.
Added in version 245.
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/.
Added in version 249.
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.
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
...
Sometimes, it is useful to allow chain invocation of another
program to list SSH authorized keys. By using the --chain option,
such a tool may be chain executed by userdbctl ssh-authorized-keys
once a lookup completes, regardless of whether an SSH key was
found or not. Example:
...
AuthorizedKeysCommand /usr/bin/userdbctl ssh-authorized-keys %u --chain /usr/bin/othertool %u
AuthorizedKeysCommandUser root
...
The above will first query the userdb database for SSH keys, and
then chain execute /usr/bin/othertool to also be queried.
On success, 0 is returned, and a non-zero failure code otherwise.
$SYSTEMD_LOG_LEVEL
The maximum log level of emitted messages (messages with a
higher log level, i.e. less important ones, will be
suppressed). Takes a comma-separated list of values. A value
may be 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. Each value may optionally be prefixed with one of
console, syslog, kmsg or journal followed by a colon to set
the maximum log level for that specific log target (e.g.
SYSTEMD_LOG_LEVEL=debug,console:info specifies to log at debug
level except when logging to the console which should be at
info level). Note that the global maximum log level takes
priority over any per target maximum log levels.
$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_LOG_RATELIMIT_KMSG
Whether to ratelimit kmsg or not. Takes a boolean. Defaults to
"true". If disabled, systemd will not ratelimit messages
written to kmsg.
$SYSTEMD_PAGER, $PAGER
Pager to use when --no-pager is not given. $SYSTEMD_PAGER is
used if set; otherwise $PAGER is used. If neither
$SYSTEMD_PAGER nor $PAGER are set, a set of well-known pager
implementations is tried in turn, including less(1) and
more(1), until one is found. If no pager implementation is
discovered, no pager is invoked. Setting those environment
variables to an empty string or the value "cat" is equivalent
to passing --no-pager.
Note: if $SYSTEMD_PAGERSECURE is not set, $SYSTEMD_PAGER and
$PAGER can only be used to disable the pager (with "cat" or
""), and are otherwise ignored.
$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.
Note that setting the regular $LESS environment variable has
no effect for less invocations by systemd tools.
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).
Note that setting the regular $LESSCHARSET environment
variable has no effect for less invocations by systemd tools.
$SYSTEMD_PAGERSECURE
Common pager commands like less(1), in addition to "paging",
i.e. scrolling through the output, support opening of or
writing to other files and running arbitrary shell commands.
When commands are invoked with elevated privileges, for
example under sudo(8) or pkexec(1), the pager becomes a
security boundary. Care must be taken that only programs with
strictly limited functionality are used as pagers, and
unintended interactive features like opening or creation of
new files or starting of subprocesses are not allowed. "Secure
mode" for the pager may be enabled as described below, if the
pager supports that (most pagers are not written in a way that
takes this into consideration). It is recommended to either
explicitly enable "secure mode" or to completely disable the
pager using --no-pager or PAGER=cat when allowing untrusted
users to execute commands with elevated privileges.
This option takes a boolean argument. When set to true, the
"secure mode" of the pager is enabled. In "secure mode",
LESSSECURE=1 will be set when invoking the pager, which
instructs the pager to disable commands that open or create
new files or start new subprocesses. Currently only less(1) is
known to understand this variable and implement "secure mode".
When set to false, no limitation is placed on the pager.
Setting SYSTEMD_PAGERSECURE=0 or not removing it from the
inherited environment may allow the user to invoke arbitrary
commands.
When $SYSTEMD_PAGERSECURE is not set, systemd tools attempt to
automatically figure out if "secure mode" should be enabled
and whether the pager supports it. "Secure mode" is enabled if
the effective UID is not the same as the owner of the login
session, see geteuid(2) and sd_pid_get_owner_uid(3), or when
running under sudo(8) or similar tools ($SUDO_UID is set [4]).
In those cases, SYSTEMD_PAGERSECURE=1 will be set and pagers
which are not known to implement "secure mode" will not be
used at all. Note that this autodetection only covers the most
common mechanisms to elevate privileges and is intended as
convenience. It is recommended to explicitly set
$SYSTEMD_PAGERSECURE or disable the pager.
Note that if the $SYSTEMD_PAGER or $PAGER variables are to be
honoured, other than to disable the pager,
$SYSTEMD_PAGERSECURE must be set too.
$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.
systemd(1), systemd-userdbd.service(8), systemd-homed.service(8),
nss-systemd(8), getent(1)
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
4. It is recommended for other tools to set and check $SUDO_UID
as appropriate, treating it is a common interface.
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 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-08-11.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
systemd 258~rc2 USERDBCTL(1)
Pages that refer to this page: homectl(1), systemd.directives(7), systemd.index(7), systemd.system-credentials(7), nss-systemd(8), systemd-homed.service(8), systemd-machined.service(8), systemd-userdbd.service(8)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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