USERADD(8)                (02/07/2020)                 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 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-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

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              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.

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          -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 aging, 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 reset to avoid reusing the entry
              from a previously deleted user.

              For the compatibility with previous Debian's useradd,
              the -O option is also supported.

          -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, --no-create-home
              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

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              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 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.

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

          -P, --prefix PREFIX_DIR
              Apply changes in the PREFIX_DIR directory and use the
              configuration files from the PREFIX_DIR directory. 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.

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          -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

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              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.

          It is usually recommended to only use usernames that begin
          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_-]*[$]?

          On Debian, the only constraints are that usernames must
          neither start with a dash ('-') nor plus ('+') nor tilde
          ('~') nor contain a colon (':'), a comma (','), or a
          whitespace (space: ' ', end of line: '\n', tabulation: '\t',
          etc.). Note that using a slash ('/') may break the default
          algorithm for the definition of the user's home directory.

          Usernames may only be up to 32 characters long.

     CONFIGURATION
          The following configuration variables in /etc/login.defs

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          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.

          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

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              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.

          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.

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              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.

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          /etc/default/useradd
              Default values for account creation.

          /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 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),
          subgid(5), subuid(5), userdel(8), usermod(8).

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