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.
The new user account will be entered into the system files as needed,
the home directory will be created, and initial files copied, depending
on the command line options.
The options which apply to the useradd command are
The new user's password file comment field.
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 default_home
and use that as the login directory name.
The date on which the user account will be disabled.
The date is specified in the format YYYY-MM-DD.
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.
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.
A list of supplementary groups which the user is also a member
Each group is separated from the next by a comma, with no
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.
The user's home directory will be created if it does not exist.
The files contained in skeleton_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 skeleton_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
The default is to not create the directory and to not copy any
The encrypted password, as returned by crypt(3).
The default is to disable the account.
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.
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 99 and
greater than every other user.
Values between 0 and 99 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
The initial path prefix for a new user's home directory.
The user's name will be affixed to the end of default_home
to create the new directory name if the -d option is not
used when creating a new account.
The date on which the user account is disabled.
The number of days after a password has expired before the
account will be disabled.
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 .
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
The system administrator is responsible for placing the default
user files in the /etc/skel directory.
The adduser program is generally more friendly to use than
this one and also uses Debian policy conformant UID and GID values,
creating a home directory a with skeletal configuration, running a
custom script, and other features. It is more prefered than using
You may not add a user to an NIS group.
This must be performed on the NIS server.
/etc/passwd - user account information
/etc/shadow - secure user account information
/etc/group - group information
/etc/default/useradd - default information
/etc/skel - directory containing default files