Exercise

• Use groupadd command to create 3 groups
  • dev
  • test
  • admin

groupadd dev
groupadd test
groupadd admin

• Create 3 users
  • usr1 in Group dev with password and home directory

  useradd -g dev -d /home/usr1 -p password usr1
  

  • usr2 in Group test with password and home directory

  useradd -g test -d /home/usr2 -p password usr2
  

  • usr3 in Group admin with password and home directory

  useradd -g admin -d /home/usr3 -p password usr3
  

  • usr4 in Groups dev and test with password and home directory

  useradd -G dev,test -d /home/usr4 -p password usr4
  

• To check the user groups

su <username>
groups

• To add user to existing groups

man usermod

usermod -aG <group-name> <user-name>

• Try deleting the users using userdel and groups using groupdel

ROOT User and sudo

• Root user is super user and has access to every thing on a linux machine.
• For the non root users to perform administrative actions on linux machines, there is a file in /etc/sudoers
  • On Ubuntu Machine to give existing user permissions to sudo, add user to sudo group
  • On Redhat family (Centos, RHEL, Fedora, Amazon Linux) Machine to give existing user permissions to sudo, add user to wheel group