# useradd -h
Options:
-g, --gid GROUP name or ID of the primary group of the new
account
-G, --groups GROUPS list of supplementary groups of the new
account
-m, --create-home create the user's home directory
-s, --shell SHELL login shell of the new account
-u, --uid UID user ID of the new account
# man useradd
-m, --create-home
The user's home directory will be created if it does not exist.
-r This flag is used to create a system account. That is, a user with a UID lower than the value of
UID_MIN defined in /etc/login.defs and whose password does not expire. Note that useradd will not
create a home directory for such an user, regardless of the default setting in /etc/login.defs.
You have to specify -m option if you want a home directory for a system account to be created.
This is an option added by Red Hat
-s, --shell SHELL
The name of a new user's login shell.
-g, --gid GROUP
The group name or number of the user's initial login group.
-G, --groups GROUP1[,GROUP2,...[,GROUPN]]]
A list of supplementary groups which the user is also a member of.
-u, --uid UID
The numerical value of the user's ID. This value must be unique
useradd -u UID -g GROUP -G GROUP1,GROUP2 -s /bin/bash -d HOME_DIR USER1
# Adminuser on RHEL
useradd -G wheel USER1
useradd -u 1001 -g admin -G wheel -m USER1
# Adminuser on Ubuntu
useradd -m -s /bin/bash -G sudo USER2