User

# List all users
cat /etc/passwd
cut -d: -f1 /etc/passwd
who
users
# List system users
awk -F':' '$3 < 1000 {print $1}' /etc/passwd
# List normal users
awk -F':' '$3 >= 1000 {print $1}' /etc/passwd
# List all users
getent passwd
# List all groups
getent group

sudo adduser americio
#sudo mkhomedir_helper americio
sudo usermod -aG sudo americio
#sudo passwd americio
su americio

sudo passwd $USER_NAME

id $USERNAME
# Current logged-in user
id
# Detailed User Info (from /etc/passwd)
getent passwd $USERNAME
# User's groups
groups username

sudo groupmod -n $NEW_GROUP_NAME $OLD_GROUP_NAME

127.0.0.1       localhost
127.0.1.1       $HOST-NAME
# The following lines are desirable for IPv6 capable hosts
::1     ip6-localhost   ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

sudo hostnamectl set-hostname $HOST-NAME