In Ubuntu the root user is disabled for safety.
Management tasks that require root access can be completed by using the sudo command by an user who is in the admin group.
The user created during the installtion process is automatically added to the admin group.
Creating and deleting groups
To create a group:
sudo addgroup groupname
To delete a group:
sudo delgroup groupname
To add a user to a group:
sudo adduser username groupname
By default, all new home directories are accessible by everyone. You can enforce non-default access rights to new home directories by editing /etc/adduser.conf
The contents of this directory are modelled after the
contents of /etc/skel.
Change “DIRMODE=0755”to “DIRMODE=0750”
You can enforce strong user passwords by editing the password policy file /etc/pam.d/common-password.
For example, to enforce a password with minimum 6 characters, edit the password line to look like this:
password required pam_unix.so nullok obscure min=6 max=8 md5
To see the password expiry value for a user, use the "chage" command:
sudo chage -l username
To make changes:
sudo chage username
The chage tool is for changing password expiration date.