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:

       --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. The directory
	   HOME_DIR is not created by default. However it will be created for
	   non-system users if either the -m flag is specifed or CREATE_HOME
	   in login.defs is set to true. However, it will never be created if
	   the -M flag is specified.

       -D, --defaults
	   See below, the subsection "Changing the default values".

       -e, --expiredate EXPIRE_DATE
	   Sets the date on which the user account will be disabled. The value
	   can be specified as a date in the YYYY-MM-DD format or as a number
	   of days since 1970-01-01. The date is interpreted using the UTC
	   timezone.

	   If not specified, useradd uses 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 a password exceeds its maximum age
	   before the user account gets locked. If the user does not change
	   their password within this period of time, their account becomes
	   inactive. This value is stored in the shadow password file. For
	   more information, see shadow(5).

	   A value of 0 disables the account when the password expires, with
	   no delay.

	   A value of -1 empties the respective field in the shadow password
	   file, which means that the inactivity period is not enforced.

	   If not specified, useradd uses the default inactivity period
	   specified by the INACTIVE variable in /etc/default/useradd, or -1
	   by default if no value is specified.

       -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 1000 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
	   specifies the number of days after a password expires during which
	   the user can still log in. After this period, the account is
	   locked.

	   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.

       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 4.18.0		  06/27/2025			    USERADD(8)