usermod

• Change a user

# Add user to a group
usermod -G "group" "user" # The user is removed from all the other groups

# Add user to another group (append)
usermod -aG "group" "user"
usermod -aG sudo spiderman # Add spiderman to the group sudo, now it can sudo commands

# Remove user from group
gpasswd -d "user" "group"