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 -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 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 bahavior 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.

       -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

	   Note: -K UID_MIN=10,UID_MAX=499 doesn't work yet.

       -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.

	   useradd will create the home directory unless CREATE_HOME in
	   /etc/login.defs is set to no.

       -M
	   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 -o 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 choosen 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.

       -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 999 and
	   greater than every other user. Values between 0 and 999 are
	   typically reserved for system accounts.

       -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 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 overriden
	   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.

       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.

       SYS_UID_MAX (number), SYS_UID_MIN (number)
	   Range of user IDs used for the creation of system users by useradd
	   or newusers.

       UID_MAX (number), UID_MIN (number)
	   Range of user IDs used for the creation of regular users by useradd
	   or newusers.

       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 overriden 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

       13
	   can't create mail spool

       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).



System Management Commands	  07/24/2009			    USERADD(8)