User and Group Managment

Key Goals

• Managing users’ and groups’ (local) life cycle
• Manage passwords
• Identify linux users

Content

• Identify linux users:

  • id

• Managing users:

  • /etc/passwd
  • useradd
  • usermod
  • userdel
  • chsh

• Managing users’ passwords:

  • /etc/shadow
  • passwd
  • chpasswd
  • chage

• Users’s defaults:

  • /etc/login.defs

• Managing groups:

  • /etc/group
  • groupadd
  • groupmod
  • groupdel
  • newgrp
  • chgrp

• Managing groups’ passwords:

  • /etc/gshadow
  • gpasswd

Exircises

• Use the above commands to:

  • Create: user1, user2
  • Create a password for user1.
  • Create: group1, group2
  • Assign user1 to group1 and group2
  • List user1’s secondary groups
  • Create a password for group2.

• In which usecase would someone run chmod g+s against some new dirctory?
• Modify the /etc/skel directory to contain some new files and verify it by creating a new user - user1.
• Why the /etc/passwd doesn’t contain the users’ passowrds?