CentOS user and user group

Create user and add to the esiting group:

/usr/sbin/useradd -G {group-name} username

if the group does not exist, create it first:

groupadd group_name

If you do not use the group option then the user will be assigned to thegroup with the same name user name.

Remove a user:

sudo /usr/sbin/userdel

User and group related files:

cat /etc/passwd

cat /etc/gshdow