How To Create User Account In Unix

1) Login the system as root.
2) cd /usr/sbin
3) Enter the following at the shell prompt to create a new account:
useradd [login name] -g [initial group name] -G [supplementary group names] -p [password]
4) You need to give the new user a password for the new account. Enter the following command:
passwd login_name
You will be asked to enter a password for login_name.

userdel - to delete an account

groups - to list all group names for the current user

Add an existing user to an existing group

usermod -a -G groupid userid

Change an existing user primary group

usermod -g groupid

Find out which group a user belongs to

id userid
groups userid

List all users (even those not logged in)

cat /etc/passwd | cut -d ":" -f1