ADDUSER(8) System Manager's Manual ADDUSER(8)
NAME
adduser, addgroup - add or manipulate users or groups
SYNOPSIS
adduser [--add-extra-groups] [--allow-all-names] [--allow-bad-names]
[--comment comment] [--conf file] [--debug] [--disabled-login]
[--disabled-password] [--firstgid id] [--firstuid id]
[--gid id] [--home dir] [--ingroup group] [--lastgid id]
[--lastuid id] [--no-create-home] [--shell shell] [--quiet]
[--uid id] [--verbose] user
adduser --system [--comment comment] [--conf file] [--debug] [--gid id]
[--group] [--home dir] [--ingroup group] [--no-create-home]
[--shell shell] [--uid id] [--quiet] [--verbose] user
adduser --group [--conf file] [--debug] [--firstgid id] [--gid ID]
[--lastgid id] [--quiet] [--verbose] group
addgroup [--conf file] [--debug] [--firstgid id] [--gid ID]
[--lastgid id] [--quiet] [--verbose] group
addgroup --system [--gid id] [--conf file] [--quiet] [--verbose] group
adduser [--conf file] [--debug] [--quiet] [--verbose] user group
adduser --help
adduser --version
DESCRIPTION
adduser and addgroup add users and groups to the system according to
command line options and configuration information in /etc/ad-
duser.conf. They are friendlier front ends to the low level tools like
useradd, groupadd and usermod programs, by default choosing Debian pol-
icy conformant UID and GID values, creating a home directory with
skeletal configuration, running a custom script, and other features.
adduser and addgroup are intended as a policy layer, making it easier
for package maintainers and local administrators to create local system
accounts in the way Debian expects them to be created, taking the bur-
den to adapt to the probably changing specifications of Debian policy.
adduser --system takes special attention on just needing a single call
in the package maintainer scripts without any conditional wrappers, er-
ror suppression or other scaffolding.
adduser honors the distinction between dynamically allocated system
users and groups and dynamically allocated user accounts that is docu-
mented in Debian Policy, Chapter 9.2.2.
For a full list and explanations of all options, see the OPTIONS sec-
tion.
adduser and addgroup can be run in one of five modes:
Add a normal user
If called with one non-option argument and without the --system or
--group options, adduser will add a normal user, that means a dynami-
cally allocated user account in the sense of Debian Policy. This is
commonly referred to in adduser as a non-system user.
adduser will choose the first available UID from the range specified by
FIRST_UID and LAST_UID in the configuration file. The range may be
overridden with the --firstuid and --lastuid options. Finally, the UID
can be set fully manually with the --uid option.
By default, each user is given a corresponding group with the same
name. This is commonly called Usergroups and allows group writable di-
rectories to be easily maintained by placing the appropriate users in
the new group, setting the set-group-ID bit in the directory, and en-
suring that all users use a umask of 002.
For a usergroup, adduser will choose the first available GID from the
range specified by FIRST_GID and LAST_GID in the configuration file.
The range may be overridden with the --firstgid and --lastgid options.
Finally, the GID can be set fully manually with the --gid option.
The interaction between USERS_GID, USERS_GROUP, and USERGROUPS is ex-
plained in detail in adduser.conf(5).
Users' primary groups can also be overridden from the command line with
the --gid or --ingroup options to set the group by id or name, respec-
tively. Also, users can be added to one or more supplemental groups
defined as EXTRA_GROUPS in the configuration file either by setting
ADD_EXTRA_GROUPS to 1 in the configuration file, or by passing
--add-extra-groups on the command line.
adduser will copy files from /etc/skel into the home directory and
prompt for the comment field and a password if those functions have not
been turned off / overridden from the command line.
UID, comment, home directory and shell might be pre-determined with the
UID_POOL and GID_POOL option, documented in adduser.conf(5).
Add a system user
If called with one non-option argument and the --system option, adduser
will add a dynamically allocated system user, often abbreviated as sys-
tem user in the context of the adduser package.
adduser will choose the first available UID from the range specified by
FIRST_SYSTEM_UID and LAST_SYSTEM_UID in the configuration file. This
can be overridden with the --uid option.
By default, system users are placed in the nogroup group. To place the
new system user in an already existing group, use the --gid or --in-
group options. If the --group is given and the identically named group
does not already exist, it is created with the same ID.
If no home directory is specified, the default home directory for a new
system user is /nonexistent. This directory should never exist on any
Debian system, and adduser will never create it automatically.
Unless a shell is explicitly set with the --shell option, the new sys-
tem user will have the shell set to /usr/sbin/nologin. adduser --sys-
tem does not set a password for the new account. Skeletal configura-
tion files are not copied.
Other options will behave as for the creation of a normal user. The
files referenced by UID_POOL and GID_POOL do also work.
Add a group
If adduser is called with the --group option and without the --system
option, or addgroup is called respectively, a user group will be added.
A dynamically allocated system group, often abbreviated as system group
in the context of the adduser package, will be created if adduser is
called with the --system option.
A GID will be chosen from the respective range specified for GIDs in
the configuration file (FIRST_GID, LAST_GID, FIRST_SYSTEM_GID,
LAST_SYSTEM_GID). To override that mechanism, you can give the GID us-
ing the --gid option.
For non-system groups, the range specified in the configuration file
may be overridden with the --firstgid and --lastgid options.
The group is created with no members.
Add an existing user to an existing group
If called with two non-option arguments, adduser will add an existing
user to an existing group.
OPTIONS
Different modes of adduser allow different options. If no valid modes
are listed for a option, it is accepted in all modes.
Short versions for certain options may exist for historical reasons.
They are going to stay supported, but are removed from the documenta-
tion. Users are advised to migrate to the long version of options.
--add-extra-groups
Add new user to extra groups defined in the configuration files'
EXTRA_GROUPS setting. The old spelling --add_extra_groups is
deprecated and will be supported in Debian bookworm only. Valid
Modes: adduser, adduser --system.
--allow-all-names
Allow any user- and groupname which is supported by the underly-
ing useradd(8), including names containing non-ASCII characters.
See VALID NAMES in adduser.conf(5). Valid Modes: adduser, ad-
duser --system, addgroup, addgroup --system.
--allow-bad-names
Disable NAME_REGEX and SYS_NAME_REGEX check of names. Only a
weaker check for validity of the name is applied. See VALID
NAMES in adduser.conf(5). Valid Modes: adduser, adduser --sys-
tem, addgroup, addgroup --system.
--comment comment
Set the comment field for the new entry generated. adduser will
not ask for the information if this option is given. This field
is also known under the name GECOS field and contains informa-
tion that is used by the finger(1) command. This used to be the
--gecos option, which is deprecated and will be removed after
Debian bookworm. Valid Modes: adduser, adduser --system.
--conf file
Use file instead of /etc/adduser.conf. Multiple --conf options
can be given.
--debug
Activate debugging code.
--disabled-login
--disabled-password
Do not run passwd(1) to set a password. In most situations, lo-
gins are still possible though (for example using SSH keys or
through PAM) for reasons that are beyond adduser's scope.
--disabled-login will additionally set the shell to
/usr/sbin/nologin. Valid Mode: adduser.
--firstuid ID
--lastuid ID
--firstgid ID
--lastgid ID
Override the first UID / last UID / first GID / last GID in the
range that the uid is chosen from (FIRST_UID, LAST_UID,
FIRST_GID and LAST_GID, FIRST_SYSTEM_UID, LAST_SYSTEM_UID,
FIRST_SYSTEM_GID and LAST_SYSTEM_GID in the configuration file).
If a group is created as a usergroup, --firstgid and --lastgid
are ignored. The group gets the same ID as the user. Valid
Modes: adduser, adduser --system, for --firstgid and --lastgid
also addgroup.
--force-badname
--allow-badname
These are the deprecated forms of --allow-bad-names. It will be
removed during the release cycle of the Debian release after
bookworm.
--gid ID
When creating a group, this option sets the group ID number of
the new group to GID. When creating a user, this option sets
the primary group ID number of the new user to GID. Valid
Modes: adduser, adduser --system, addgroup, addgroup --system.
--group
Using this option in adduser --system indicates that the new
user should get an identically named group as its primary group.
If that identically named group is not already present, it is
created. If not combined with --system, a group with the given
name is created. The latter is the default action if the pro-
gram is invoked as addgroup. Valid Modes: adduser --system, ad-
dgroup, addgroup --system.
--help Display brief instructions.
--home dir
Use dir as the user's home directory, rather than the default
specified by the configuration file (or /nonexistent if adduser
--system is used). If the directory does not exist, it is cre-
ated. Valid Modes: adduser, adduser --system.
--ingroup GROUP
When creating a user, this option sets the primary group ID num-
ber of the new user to the GID of the named group. Unlike with
the --gid option, the group is specified here by name rather
than by numeric ID number. The group must already exist. Valid
Modes: adduser, adduser --system.
--lastuid ID
--lastgid ID
Override the last UID / last GID. See --firstuid.
--no-create-home
Do not create a home directory for the new user. Note that the
pathname for the new user's home directory will still be entered
in the appropriate field in the /etc/passwd file. The use of
this option does not imply that this field should be empty.
Rather, it indicates to adduser that some other mechanism will
be responsible for initializing the new user's home directory.
Valid Modes: adduser, adduser --system.
--quiet
Suppress informational messages, only show warnings and errors.
--shell shell
Use shell as the user's login shell, rather than the default
specified by the configuration file (or /usr/sbin/nologin if ad-
duser --system is used). Valid Modes: adduser, adduser --sys-
tem.
--system
Nomally, adduser creates dynamically allocated user accounts and
groups as defined in Debian Policy, Chapter 9.2.2. With this
option, adduser creates a dynamically allocated system user and
group and changes its mode respectively. Valid Modes: adduser,
addgroup.
--uid ID
Force the new userid to be the given number. adduser will fail
if the userid is already taken. Valid Modes: adduser, adduser
--system.
--verbose
Be more verbose.
-v , --version
Display version and copyright information.
EXIT VALUES
0 Success: The user or group exists as specified. This can have 2
causes: The user or group was created by this call to adduser or
the user or group was already present on the system as specified
before adduser was invoked. If adduser --system is invoked for
a user already existing as a system user, it will also return 0.
1 Creating the non-system user or group failed because it was al-
ready present. The username or groupname was rejected because
of a mismatch with the configured regular expressions, see ad-
duser.conf(5). adduser has been aborted by a signal.
Or for many other yet undocumented reasons which are printed to console
then. You may then consider to remove --quiet to make adduser more
verbose.
SECURITY
adduser needs root privileges and offers, via the --conf command line
option to use different configuration files. Do not use sudo(8) or
similar tools to give partial privileges to adduser with restricted
command line parameters. This is easy to circumvent and might allow
users to create arbitrary accounts. If you want this, consider writing
your own wrapper script and giving privileges to execute that script.
FILES
/etc/adduser.conf
Default configuration file for adduser(8) and addgroup(8)
/usr/local/sbin/adduser.local
Optional custom add-ons, see adduser.local(8)
NOTES
Unfortunately, the term system account suffers from double use in De-
bian. It both means an account for the actual Debian system, distin-
guishing itself from an application account which might exist in the
user database of some application running on Debian. A system account
in this definition has the potential to log in to the actual system,
has a UID, can be member in system groups, can own files and processes.
Debian Policy, au contraire, in its Chapter 9.2.2, makes a distinguish-
ment of dynamically allocated system users and groups and dynamically
allocated user accounts, meaning in both cases special instances of
system accounts. Care must be taken to not confuse this terminology.
Since adduser and deluser(8) never address application accounts and ev-
erything in this package concerns system accounts here, the usage of
the terms user account and system account is actually not ambiguous in
the context of this package. For clarity, this document uses the defi-
nition local system account or group if the distinction to application
accounts or accounts managed in a directory service is needed.
adduser used to have the vision to be the universal front end to the
various directory services for creation and deletion of regular and
system accounts in Debian since the 1990ies. This vision has been
abandoned as of 2022. The rationale behind this includes: that in
practice, a small server system is not going to have write access to an
enterprise-wide directory service anyway, that locally installed pack-
ages are hard to manage with centrally controlled system accounts, that
enterprise directory services have their own management processes any-
way and that the personpower of the adduser team is unlikely to be ever
strong enough to write and maintain support for the plethora of direc-
tory services that need support.
adduser will constrict itself to being a policy layer for the manage-
ment of local system accounts, using the tools from the password pack-
age for the actual work.
BUGS
Inconsistent use of terminology around the term system account in docs
and code is a bug. Please report this and allow us to improve our
docs.
adduser takes special attention to be directly usable in Debian main-
tainer scripts without conditional wrappers, error suppression and
other scaffolding. The only thing that the package maintainer should
need to code is a check for the presence of the executable in the
postrm script. The adduser maintainers consider the need for addi-
tional scaffolding a bug and encourage their fellow Debian package
maintainers to file bugs against the adduser package in this case.
SEE ALSO
adduser.conf(5), deluser(8), groupadd(8), useradd(8), usermod(8), De-
bian Policy 9.2.2.
Debian GNU/Linux ADDUSER(8)
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