Manual: useradd
USERADD(8) System Management Commands USERADD(8)
NAME
useradd - create a new user or update default new user information
SYNOPSIS
useradd [options] LOGIN
useradd -D
useradd -D [options]
DESCRIPTION
useradd is a low level utility for adding users. On Debian, administrators should usually use
adduser(8) instead.
When invoked without the -D option, the useradd command creates a new user account using the values
specified on the command line plus the default values from the system. Depending on command line
options, the useradd command will update system files and may also create the new user's home
directory and copy initial files.
By default, a group will also be created for the new user (see -g, -N, -U, and USERGROUPS_ENAB).
OPTIONS
The options which apply to the useradd command are:
--badname
Allow names that do not conform to standards.
-b, --base-dir BASE_DIR
The default base directory for the system if -d HOME_DIR is not specified. BASE_DIR is
concatenated with the account name to define the home directory.
If this option is not specified, useradd will use the base directory specified by the HOME
variable in /etc/default/useradd, or /home by default.
-c, --comment COMMENT
Any text string. It is generally a short description of the account, and is currently used as the
field for the user's full name.
-d, --home-dir HOME_DIR
The new user will be created using HOME_DIR as the value for the user's login directory. The
default is to append the LOGIN name to BASE_DIR and use that as the login directory name. If the
directory HOME_DIR does not exist, then it will be created unless the -M option is specified.
-D, --defaults
See below, the subsection "Changing the default values".
-e, --expiredate EXPIRE_DATE
The date on which the user account will be disabled. The date is specified in the format
YYYY-MM-DD.
If not specified, useradd will use the default expiry date specified by the EXPIRE variable in
/etc/default/useradd, or an empty string (no expiry) by default.
-f, --inactive INACTIVE
defines the number of days after the password exceeded its maximum age where the user is expected
to replace this password. The value is stored in the shadow password file. An input of 0 will
disable an expired password with no delay. An input of -1 will blank the respective field in the
shadow password file. See shadow(5)for more information.
If not specified, useradd will use the default inactivity period specified by the INACTIVE
variable in /etc/default/useradd, or -1 by default.
-F, --add-subids-for-system
Update /etc/subuid and /etc/subgid even when creating a system account with -r option.
-g, --gid GROUP
The name or the number of the user's primary group. The group name must exist. A group number
must refer to an already existing group.
If not specified, the behavior of useradd will depend on the USERGROUPS_ENAB variable in
/etc/login.defs. If this variable is set to yes (or -U/--user-group is specified on the command
line), a group will be created for the user, with the same name as the loginname. If the variable
is set to no (or -N/--no-user-group is specified on the command line), useradd will set the
primary group of the new user to the value specified by the GROUP variable in
/etc/default/useradd, or 100 by default.
-G, --groups GROUP1[,GROUP2,...[,GROUPN]]]
A list of supplementary groups which the user is also a member of. Each group is separated from
the next by a comma, with no intervening whitespace. The groups are subject to the same
restrictions as the group given with the -g option. The default is for the user to belong only to
the initial group. In addition to passing in the -G flag, you can add the option GROUPS to the
file /etc/default/useradd which in turn will add all users to those supplementary groups.
-h, --help
Display help message and exit.
-k, --skel SKEL_DIR
The skeleton directory, which contains files and directories to be copied in the user's home
directory, when the home directory is created by useradd.
This option is only valid if the -m (or --create-home) option is specified.
If this option is not set, the skeleton directory is defined by the SKEL variable in
/etc/default/useradd or, by default, /etc/skel.
Absolute symlinks that link back to the skel directory will have the /etc/skel prefix replaced
with the user's home directory.
If possible, the ACLs and extended attributes are copied.
-K, --key KEY=VALUE
Overrides /etc/login.defs defaults (UID_MIN, UID_MAX, UMASK, PASS_MAX_DAYS and others).
Example: -K PASS_MAX_DAYS =-1 can be used when creating an account to turn off password aging.
Multiple -K options can be specified, e.g.: -K UID_MIN =100 -K UID_MAX=499
-l, --no-log-init
Do not add the user to the lastlog and faillog databases.
By default, the user's entries in the lastlog and faillog databases are reset to avoid reusing
the entry from a previously deleted user.
If this option is not specified, useradd will also consult the variable LOG_INIT in the
/etc/default/useradd if set to no the user will not be added to the lastlog and faillog
databases.
-m, --create-home
Create the user's home directory if it does not exist. The files and directories contained in the
skeleton directory (which can be defined with the -k option) will be copied to the home
directory.
By default, if this option is not specified and CREATE_HOME is not enabled, no home directories
are created.
The directory where the user's home directory is created must exist and have proper SELinux
context and permissions. Otherwise the user's home directory cannot be created or accessed.
-M, --no-create-home
Do not create the user's home directory, even if the system wide setting from /etc/login.defs
(CREATE_HOME) is set to yes.
-N, --no-user-group
Do not create a group with the same name as the user, but add the user to the group specified by
the -g option or by the GROUP variable in /etc/default/useradd.
The default behavior (if the -g, -N, and -U options are not specified) is defined by the
USERGROUPS_ENAB variable in /etc/login.defs.
-o, --non-unique
allows the creation of an account with an already existing UID.
This option is only valid in combination with the -u option. As a user identity serves as key to
map between users on one hand and permissions, file ownerships and other aspects that determine
the system's behavior on the other hand, more than one login name will access the account of the
given UID.
-p, --password PASSWORD
defines an initial password for the account. PASSWORD is expected to be encrypted, as returned by
crypt (3). Within a shell script, this option allows to create efficiently batches of users.
Without this option, the new account will be locked and with no password defined, i.e. a single
exclamation mark in the respective field of /etc/shadow. This is a state where the user won't be
able to access the account or to define a password himself.
Note:Avoid this option on the command line because the password (or encrypted password) will be
visible by users listing the processes.
You should make sure the password respects the system's password policy.
-r, --system
Create a system account.
System users will be created with no aging information in /etc/shadow, and their numeric
identifiers are chosen in the SYS_UID_MIN-SYS_UID_MAX range, defined in /etc/login.defs, instead
of UID_MIN-UID_MAX (and their GID counterparts for the creation of groups).
Note that useradd will not create a home directory for such a user, regardless of the default
setting in /etc/login.defs (CREATE_HOME). You have to specify the -m options if you want a home
directory for a system account to be created.
Note that this option will not update /etc/subuid and /etc/subgid. You have to specify the -F
options if you want to update the files for a system account to be created.
-R, --root CHROOT_DIR
Apply changes in the CHROOT_DIR directory and use the configuration files from the CHROOT_DIR
directory. Only absolute paths are supported.
-P, --prefix PREFIX_DIR
Apply changes to configuration files under the root filesystem found under the directory
PREFIX_DIR. This option does not chroot and is intended for preparing a cross-compilation target.
Some limitations: NIS and LDAP users/groups are not verified. PAM authentication is using the
host files. No SELINUX support.
-s, --shell SHELL
sets the path to the user's login shell. Without this option, the system will use the SHELL
variable specified in /etc/default/useradd, or, if that is as well not set, the field for the
login shell in /etc/passwd remains empty.
-u, --uid UID
The numerical value of the user's ID. This value must be unique, unless the -o option is used.
The value must be non-negative. The default is to use the smallest ID value greater than or equal
to UID_MIN and greater than every other user.
See also the -r option and the UID_MAX description.
-U, --user-group
Create a group with the same name as the user, and add the user to this group.
The default behavior (if the -g, -N, and -U options are not specified) is defined by the
USERGROUPS_ENAB variable in /etc/login.defs.
-Z, --selinux-user SEUSER
defines the SELinux user for the new account. Without this option, SELinux uses the default user.
Note that the shadow system doesn't store the selinux-user, it uses semanage(8) for that.
--selinux-range SERANGE
defines the SELinux MLS range for the new account. Without this option, SELinux uses the default
range. Note that the shadow system doesn't store the selinux-range, it uses semanage(8) for that.
This option is only valid if the -Z (or --selinux-user) option is specified.
Changing the default values
When invoked with only the -D option, useradd will display the current default values. When invoked
with -D plus other options, useradd will update the default values for the specified options. Valid
default-changing options are:
-b, --base-dir BASE_DIR
sets the path prefix for a new user's home directory. The user's name will be affixed to the end
of BASE_DIR to form the new user's home directory name, if the -d option is not used when
creating a new account.
This option sets the HOME variable in /etc/default/useradd.
-e, --expiredate EXPIRE_DATE
sets the date on which newly created user accounts are disabled.
This option sets the EXPIRE variable in /etc/default/useradd.
-f, --inactive INACTIVE
defines the number of days after the password exceeded its maximum age where the user is expected
to replace this password. See shadow(5)for more information.
This option sets the INACTIVE variable in /etc/default/useradd.
-g, --gid GROUP
sets the default primary group for newly created users, accepting group names or a numerical
group ID. The named group must exist, and the GID must have an existing entry.
This option sets the GROUP variable in /etc/default/useradd.
-s, --shell SHELL
defines the default login shell for new users.
This option sets the SHELL variable in /etc/default/useradd.
NOTES
The system administrator is responsible for placing the default user files in the /etc/skel/
directory (or any other skeleton directory specified in /etc/default/useradd or on the command line).
CAVEATS
You may not add a user to a NIS or LDAP group. This must be performed on the corresponding server.
Similarly, if the username already exists in an external user database such as NIS or LDAP, useradd
will deny the user account creation request.
Usernames may contain only lower and upper case letters, digits, underscores, or dashes. They can end
with a dollar sign. Dashes are not allowed at the beginning of the username. Fully numeric usernames
and usernames . or .. are also disallowed. It is not recommended to use usernames beginning with .
character as their home directories will be hidden in the ls output.
On Ubuntu, the same constraints as Debian are in place, with the additional constraint that the
username cannot be fully numeric, including octal and hexadecimal syntax.
Usernames may only be up to 256 characters long.
CONFIGURATION
The following configuration variables in /etc/login.defs change the behavior of this tool:
CREATE_HOME (boolean)
Indicate if a home directory should be created by default for new users.
This setting does not apply to system users, and can be overridden on the command line.
GID_MAX (number), GID_MIN (number)
Range of group IDs used for the creation of regular groups by useradd, groupadd, or newusers.
The default value for GID_MIN (resp. GID_MAX) is 1000 (resp. 60000).
HOME_MODE (number)
The mode for new home directories. If not specified, the UMASK is used to create the mode.
useradd and newusers use this to set the mode of the home directory they create.
LASTLOG_UID_MAX (number)
Highest user ID number for which the lastlog entries should be updated. As higher user IDs are
usually tracked by remote user identity and authentication services there is no need to create a
huge sparse lastlog file for them.
No LASTLOG_UID_MAX option present in the configuration means that there is no user ID limit for
writing lastlog entries.
MAIL_DIR (string)
The mail spool directory. This is needed to manipulate the mailbox when its corresponding user
account is modified or deleted. If not specified, a compile-time default is used. The parameter
CREATE_MAIL_SPOOL in /etc/default/useradd determines whether the mail spool should be created.
MAIL_FILE (string)
Defines the location of the users mail spool files relatively to their home directory.
The MAIL_DIR and MAIL_FILE variables are used by useradd, usermod, and userdel to create, move, or
delete the user's mail spool.
MAX_MEMBERS_PER_GROUP (number)
Maximum members per group entry. When the maximum is reached, a new group entry (line) is started
in /etc/group (with the same name, same password, and same GID).
The default value is 0, meaning that there are no limits in the number of members in a group.
This feature (split group) permits to limit the length of lines in the group file. This is useful
to make sure that lines for NIS groups are not larger than 1024 characters.
If you need to enforce such limit, you can use 25.
Note: split groups may not be supported by all tools (even in the Shadow toolsuite). You should
not use this variable unless you really need it.
PASS_MAX_DAYS (number)
The maximum number of days a password may be used. If the password is older than this, a password
change will be forced. If not specified, -1 will be assumed (which disables the restriction).
PASS_MIN_DAYS (number)
The minimum number of days allowed between password changes. Any password changes attempted
sooner than this will be rejected. If not specified, 0 will be assumed (which disables the
restriction).
PASS_WARN_AGE (number)
The number of days warning given before a password expires. A zero means warning is given only
upon the day of expiration, a value of -1 means no warning is given. If not specified, no warning
will be provided.
SUB_GID_MIN (number), SUB_GID_MAX (number), SUB_GID_COUNT (number)
If /etc/subuid exists, the commands useradd and newusers (unless the user already have
subordinate group IDs) allocate SUB_GID_COUNT unused group IDs from the range SUB_GID_MIN to
SUB_GID_MAX for each new user.
The default values for SUB_GID_MIN, SUB_GID_MAX, SUB_GID_COUNT are respectively 100000, 600100000
and 65536.
SUB_UID_MIN (number), SUB_UID_MAX (number), SUB_UID_COUNT (number)
If /etc/subuid exists, the commands useradd and newusers (unless the user already have
subordinate user IDs) allocate SUB_UID_COUNT unused user IDs from the range SUB_UID_MIN to
SUB_UID_MAX for each new user.
The default values for SUB_UID_MIN, SUB_UID_MAX, SUB_UID_COUNT are respectively 100000, 600100000
and 65536.
SYS_GID_MAX (number), SYS_GID_MIN (number)
Range of group IDs used for the creation of system groups by useradd, groupadd, or newusers.
The default value for SYS_GID_MIN (resp. SYS_GID_MAX) is 101 (resp. GID_MIN-1).
SYS_UID_MAX (number), SYS_UID_MIN (number)
Range of user IDs used for the creation of system users by useradd or newusers.
The default value for SYS_UID_MIN (resp. SYS_UID_MAX) is 101 (resp. UID_MIN-1).
UID_MAX (number), UID_MIN (number)
Range of user IDs used for the creation of regular users by useradd or newusers.
The default value for UID_MIN (resp. UID_MAX) is 1000 (resp. 60000).
UMASK (number)
The file mode creation mask is initialized to this value. If not specified, the mask will be
initialized to 022.
useradd and newusers use this mask to set the mode of the home directory they create if HOME_MODE
is not set.
It is also used by pam_umask as the default umask value.
USERGROUPS_ENAB (boolean)
If set to yes, userdel will remove the user's group if it contains no more members, and useradd
will create by default a group with the name of the user.
FILES
/etc/passwd
User account information.
/etc/shadow
Secure user account information.
/etc/group
Group account information.
/etc/gshadow
Secure group account information.
/etc/default/useradd
Default values for account creation.
/etc/shadow-maint/useradd-pre.d/*, /etc/shadow-maint/useradd-post.d/*
Run-part files to execute during user addition. The environment variable ACTION will be populated
with useradd and SUBJECT with the username. useradd-pre.d will be executed prior to any user
addition. useradd-post.d will execute after user addition. If a script exits non-zero then
execution will terminate.
/etc/skel/
Directory containing default files.
/etc/subgid
Per user subordinate group IDs.
/etc/subuid
Per user subordinate user IDs.
/etc/login.defs
Shadow password suite configuration.
EXIT VALUES
The useradd command exits with the following values:
0
success
1
can't update password file
2
invalid command syntax
3
invalid argument to option
4
UID already in use (and no -o)
6
specified group doesn't exist
9
username or group name already in use
10
can't update group file
12
can't create home directory
14
can't update SELinux user mapping
19
invalid user or group name
SEE ALSO
chfn(1), chsh(1), passwd(1), crypt(3), groupadd(8), groupdel(8), groupmod(8), login.defs(5),
newusers(8), subgid(5), subuid(5), userdel(8), usermod(8).
shadow-utils 4.17.4 02/02/2026 USERADD(8)