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. The BASE_DIR must exist otherwise the home directory cannot
be created.
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-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.
-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.
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.
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
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 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
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 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
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
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).
shadow-utils 4.1.5.1 11/05/2016 USERADD(8)
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