USERADD(8) System Management Commands USERADD(8)NAMEuseradd - create a new user or update default new user information
SYNOPSISuseradd [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 and 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.
OPTIONS
The options which apply to the useradd command are:
-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.
-b, --base-dir BASE_DIR
The default base directory for the system if -d 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.
-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.
-e, --expiredate EXPIRE_DATE
The date on which the user account will be disabled. The date is
specified in the format YYYY-MM-DD.
-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. The default value is -1.
-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. The default group number is 1 or whatever is
specified in /etc/default/useradd.
-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.
-m, --create-home
The user's home directory will be created if it does not exist.
The files contained in SKEL_DIR will be copied to the home
directory if the -k option is used, otherwise the files
contained in /etc/skel will be used instead. Any directories
contained in SKEL_DIR or /etc/skel will be created in the user's
home directory as well. The -k option is only valid in
conjunction with the -m option. The default is to not create the
directory and to not copy any files.
-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.
-o, --non-unique
Allow the creation of a user account with a duplicate
(non-unique) UID.
-p, --password PASSWORD
The encrypted password, as returned by crypt(3). The default is
to disable the account.
-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.
-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.
Changing the default values
When invoked with the -D option, useradd will either display the
current default values, or update the default values from the command
line. The valid options are
-b HOME_DIR
The initial path prefix for a new user's home directory. The
user's name will be affixed to the end of HOME_DIR to create the
new directory name if the -d option is not used when creating a
new account.
-e EXPIRE_DATE
The date on which the user account is disabled.
-f INACTIVE
The number of days after a password has expired before the
account will be disabled.
-g, --gid GROUP
The group name or ID for a new user's initial group. The named
group must exist, and a numerical group ID must have an existing
entry.
-s, --shell SHELL
The name of the new user's login shell. The named program will
be used for all future new user accounts.
If no options are specified, useradd displays the current default
values.
NOTES
The system administrator is responsible for placing the default user
files in the /etc/skel/ directory.
CAVEATS
You may not add a user to a NIS group. This must be performed on the
NIS server.
Similarly, if the username already exists in an external user database
such as NIS, useradd will deny the user account creation request.
Usernames must begin with a lower case letter or an underscore, and
only lower case letters, underscores, dashes, and dollar signs may
follow. In regular expression terms: [a-z_][a-z0-9_-]*[$]
FILES
/etc/passwd
user account information
/etc/shadow
secure user account information
/etc/group
group account information
/etc/default/useradd
default information
/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
SEE ALSOchfn(1), chsh(1), passwd(1), crypt(3), groupadd(8), groupdel(8),
groupmod(8), login.defs(5), userdel(8), usermod(8).
System Management Commands 01/22/2006 USERADD(8)
