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

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:

-b, –base-dir BASE_DIR
The default base directory for the system if -dHOME_DIR is not
specified.  BASE_DIR is concatenated with the account name to
define the home directory. If the -m option is not used, BASE_DIR
must exist.

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
login, and is currently used as the field for the user’s full
name.

-d, –home 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. The
directory HOME_DIR does not have to exist but will not be created
if it is missing.

-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
The number of days after a password expires until the account is
permanently disabled. A value of 0 disables the account as soon
as the password has expired, and a value of -1 disables the
feature.

If not specified, useradd will use the default inactivity period
specified by the INACTIVE variable in /etc/default/useradd, or -1
by default.

-g, –gid GROUP
The group name or number of the user’s initial login 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 her
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.

-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.

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 system
account to turn off password ageing, even though system account
has no password at all. 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 resetted to avoid reusing the entry from a
previously deleted user.

-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.

-M
Do no 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
Allow the creation of a user account with a duplicate
(non-unique) UID.

This option is only valid in combination with the -u option.

-p, –password PASSWORD
The encrypted password, as returned by crypt(3). The default is
to disable the password.

Note: This option is not recommended 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 an
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.

-R, –root CHROOT_DIR
Apply changes in the CHROOT_DIR directory and use the
configuration files from the CHROOT_DIR directory.

-s, –shell SHELL
The name of the user’s login shell. The default is to leave this
field blank, which causes the system to select the default login
shell specified by the SHELL variable in /etc/default/useradd, or
an empty string by default.

-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
The SELinux user for the user’s login. The default is to leave
this field blank, which causes the system to select the default
SELinux user.

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
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
The date on which the user account is disabled.

This option sets the EXPIRE variable in /etc/default/useradd.

-f, –inactive INACTIVE
The number of days after a password has expired before the
account will be disabled.

This option sets the INACTIVE variable in /etc/default/useradd.

-g, –gid GROUP
The group name or ID for a new user’s initial group (when the
-N/–no-user-group is used or when the USERGROUPS_ENAB variable
is set to no in /etc/login.defs). The named group must exist, and
a numerical group ID must have an existing entry.

This option sets the GROUP variable in /etc/default/useradd.

-s, –shell SHELL
The name of a new user’s login shell.

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 must start with a lower case letter or an underscore,
followed by lower case letters, digits, underscores, or dashes. They
can end with a dollar sign. In regular expression terms:
[a-z_][a-z0-9_-]*[$]?

Usernames may only be up to 32 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).

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.

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.

If MAIL_CHECK_ENAB is set to yes, they are also used to define the
MAIL environment variable.

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, -1 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
negative value means no warning is given. If not specified, no
warning will be provided.

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

It is also used by login to define users’ initial umask. Note
that this mask can be overridden by the user’s GECOS line (if
QUOTAS_ENAB is set) or by the specification of a limit with the K
identifier in limits(5).

USERGROUPS_ENAB (boolean)
Enable setting of the umask group bits to be the same as owner
bits (examples: 022 -> 002, 077 -> 007) for non-root users, if
the uid is the same as gid, and username is the same as the
primary group name.

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/skel/
Directory containing default files.

/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 already in use

10
can’t update group file

12
can’t create home directory

14
can’t update SELinux user mapping

SEE ALSO

chfn(1), chsh(1), passwd(1), crypt(3), groupadd(8), groupdel(8),
groupmod(8), login.defs(5), newusers(8), userdel(8), usermod(8).

COLOPHON

This page is part of the shadow-utils (utilities for managing
accounts and shadow password files) project.  Information about the
project can be found at ⟨http://pkg-shadow.alioth.debian.org/⟩.  If
you have a bug report for this manual page, see
⟨http://pkg-shadow.alioth.debian.org/getinvolved.php⟩.  This page was
obtained from the project’s upstream Subversion repository
(svn://anonscm.debian.org/pkg-shadow/) on 2014-12-30.  If you dis‐
cover 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 [email protected]

shadow-utils 4.1.5.1             01/27/2014                       USERADD(8)

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