DOKK / manpages / debian 13 / adduser / adduser.conf.5.en
ADDUSER.CONF(5) File Formats Manual ADDUSER.CONF(5)

/etc/adduser.conf - configuration file for adduser(8) and addgroup(8)

The file /etc/adduser.conf contains defaults for the programs adduser(8), addgroup(8), deluser(8) and delgroup(8). Each line holds a single value pair in the form option = value. Double or single quotes are allowed around the value, as is whitespace around the equals sign. Comment lines must have a hash sign (#) in the first column.

The valid configuration options are:

Minimum priority for messages logged to syslog/journal and the console, respectively. See LOGGING in adduser(8). Defaults to warn for STDOUTMSGLEVEL and STDERRMSGLEVEL and info for LOGMSGLEVEL.
Setting this to something other than 0 will cause adduser to add newly created non-system users to the list of groups defined by EXTRA_GROUPS (below). Defaults to 0.
The permissions mode for home directories of non-system users that are created by adduser(8). Defaults to 0700. Note that there are potential configurations (such as ~/user web services, or in-home mail delivery) which will require changes to the default. See also SYS_DIR_MODE.
The directory in which new home directories should be created. Defaults to /home.
The login shell to be used for all new users. Defaults to /bin/bash.
This is the space-separated list of groups that new non-system users will be added to. Defaults to users.
specify an inclusive range of GIDs from which GIDs for system groups can be dynamically allocated. Defaults to 100 - 999.
specify an inclusive range of GIDs from which GIDs for non-system groups can be dynamically allocated. Defaults to 1000 - 59999.
specify an inclusive range of UIDs from which UIDs for system users can be dynamically allocated. Defaults to 100 - 999. Please note that system software, such as the users allocated by the base-passwd package, may assume that UIDs less than 100 are unallocated.
specify an inclusive range of UIDs from which UIDs for non-system users can be dynamically allocated. Defaults to 1000 - 59999.
See UID_POOL.
If this is set to yes, the home directories will be created as /home/groupname/user. Defaults to no. This option is deprecated and will be removed.
See the FIRST_ variants of the option.
If this is set to yes, then the home directories created will have an extra directory inserted which is the first letter of the loginname. For example: /home/u/user. Defaults to no. This option is deprecated and will be removed.
Non-system user- and groupnames are checked against this regular expression. If the name doesn't match this regexp, user and group creation in adduser(8) is refused unless --allow-bad-names is set. With --allow-bad-names set, weaker checks are performed. Defaults to the most conservative ^[a-zA-Z][a-zA-Z0-9_-]*\$?$. See SYS_NAME_REGEX and Valid names, below, for more information.
If set to a nonempty value, new users will have quotas copied from that user using edquota -p QUOTAUSER newuser. Defaults to the empty string.
Controls whether the UID and GID values that are listed in the pool files are truly reserved. See UID AND GID POOLS in the NOTES section. Defaults to yes.
If this is set to yes, then home directories for users with their own group (USERGROUPS = yes) will have the set-group-ID bit set. Note that this feature is deprecated and will be removed in a future version of adduser(8). Please use DIR_MODE instead. Defaults to no.
The directory from which skeletal user configuration files will be copied. Defaults to /etc/skel.
When populating the newly created home directory of a non-system user, files in SKEL matching this regex are not copied. Defaults to to (.(dpkg|ucf)-(old|new|dist)$), the regular expression matching files left over from unmerged config files.
The permissions mode for home directories of system users that are created by adduser(8). Defaults to 0755. Note that changing the default permissions for system users may cause some packages to behave unreliably, if the program relies on the default setting. See also DIR_MODE.
System user- and groupnames are checked against this regular expression. If the name doesn't match this regexp, system user and group creation in adduser is refused unless --allow-bad-names is set. With --allow-bad-names set, weaker checks are performed. Defaults to the most conservative ^[a-zA-Z_][a-zA-Z0-9_-]*\$?$. See NAME_REGEX, above, and Valid names, below, for more information.
specify a file or a directory containing UID and GID pool files. See UID AND GID POOLS in the NOTES section. Both default to empty.
Specify whether each created non-system user will be given their own group to use. Defaults to yes.
Defines the groupname or GID of the group all newly-created non-system users are placed into. If USERGROUPS is yes, the group will be added as a supplementary group; if USERGROUPS is no,, it will be the primary group. If you don't want all your users to be in one group, set USERGROUPS=yes, leave USERS_GROUP empty and set USERS_GID to "-1". USERS_GROUP defaults to users, which has GID 100 on all Debian systems since it's defined statically by the base-passwd package. It is a configuration error to define both variables even if the values are consistent.

Some installations desire that a non-system account gets preconfigured properties when it is generated. Commonly, the local admin wants to make sure that even without using a directory service, an account or a group with a certain name has the same numeric UID/GID on all systems where it exists.

To enable this feature, define configuration variables UID_POOL (for user accounts) and/or GID_POOL (for groups) in /etc/adduser.conf and install the respective files in the configured places. The value is either a file or a directory. In the latter case all files named *.conf in that directory are considered.

The file format is similar to /etc/passwd: Text lines, fields separated by a colon. The values are username/groupname (mandatory), UID/GID (mandatory), comment field (optional, useful for user IDs only), home directory (ditto), shell (ditto).

It is possible to use the same file/directory for UID_POOL and GID_POOL.

If an account / group is created, adduser(8) searches in all UID/GID pool files for a line matching the name of the newly created account and uses the data found there to initialize the new account instead of using the defaults. Settings may be overridden from the command line.

In the default configuration, UID and GID values listed in the pool will be reserved and thus not be used by the normal UID and GID selection processes. This is usually what you'd want. With the RESERVE_UID_POOL and RESERVE_GID_POOL configuration options, you can switch this behavior off if you want pooled UIDs and GIDs used by regular accounts. This might cause conflicts and cause your pool UIDs and GIDs to be used by accounts that are not in the pool.

/etc/adduser.conf

deluser.conf(5), addgroup(8), adduser(8), delgroup(8), deluser(8)

Debian GNU/Linux