useradd command in linux not working as expected?

I tried to change default shell in Ubuntu 14.04 using the following command

user@MyUbuntu:~$ sudo useradd -D -s /bin/tcsh
user@MyUbuntu:~$ sudo useradd -D
GROUP=101
HOME=/home
INACTIVE=-1
EXPIRE=
SHELL=/bin/sh
SKEL=/etc/skel
CREATE_MAIL_SPOOL=no

Why defaults are not getting updated. I reboot the pc, but values still not updating. Why ?

Update: I don't want to add a new user, i want to update some defaults using useradd command

2 Answers

Use adduser command. The adduser command is a Perl implementation of useradd (which is a C binary).

$ cat /usr/sbin/adduser | grep useradd my $useradd = &which('useradd'); &systemcall($useradd, '--extrausers', '-d', $home_dir, '-g', $ingroup_name, '-s', &systemcall($useradd, '-d', $home_dir, '-g', $ingroup_name, '-s', my $useradd = &which('useradd'); &systemcall($useradd, '--extrausers', '-d', $home_dir, '-g', $ingroup_name, '-s', &systemcall($useradd, '-d', $home_dir, '-g', $ingroup_name, '-s', # useradd without -p has left the account disabled (password string is '!')

adduser takes care of everything, i.e whether the user has been added to the /etc/passwd file or not.

For me changes are applying and I think I did same as you did.

gennu@gennu:~$ sudo useradd -D -s /bin/tcsh
gennu@gennu:~$ useradd -D
GROUP=100
HOME=/home
INACTIVE=-1
EXPIRE=
SHELL=
SKEL=/etc/skel
CREATE_MAIL_SPOOL=no
gennu@gennu:~$ sudo useradd -D
GROUP=100
HOME=/home
INACTIVE=-1
EXPIRE=
SHELL=/bin/tcsh
SKEL=/etc/skel
CREATE_MAIL_SPOOL=no
gennu@gennu:~$ 

But I didnt see changes were done in my /etc/passwd file.

gennu@gennu:~$ cat /etc/passwd | grep 'root\|gennu'
root:x:0:0:root:/root:/bin/bash
gennu:x:1000:1000:gennu,,,:/home/gennu:/bin/bash