User Management And Permissions

https://www.tecmint.com/add-users-in-linux/

https://www.cyberciti.biz/faq/create-a-user-account-on-ubuntu-linux/

#create user
sudo adduser ali --no-create-home --uid 2000


#here are all users and groups
cat /etc/passwd
cat /etc/group


#delete user and their private group in one go (with a warning issued)
sudo deluser ali


# add user to the sudo group
usermod -aG sudo mk



# rename user and group from mk2 to mk
sudo usermod -l mk mk2
sudo groupmod -n mk mk2

# change user id
sudo usermod -u 1000 mk

# change group id
sudo groupmod -g 1000 mk

# to change the home directory of a logged off user
sudo usermod -d /home/mk -m mk


# create a temporary user
sudo adduser mk2 --uid 3000

# add certain priveleges
sudo usermod -aG dialout,tty,docker,root,sudo mk2


sudo adduser mk
sudo usermod -aG dialout,tty,docker,root mk
#you can check all your subscribed groups
groups mk

# assign all groups from user ubuntu to user mk
sudo usermod -aG $(groups ubuntu | sed 's/\s\+/,/g') mk

# change user_id
sudo usermod -u 1000 mk

# change group id
sudo groupmod -g 1000 mk

# query user id and group id
id -u mk
id -g mk


#sudo without typing passwords
echo "mk     ALL=(ALL) NOPASSWD:ALL" | sudo tee -a /etc/sudoers