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Linux Administration · Module 2 of 10

Users and groups

Create users, manage groups and use sudo.

📖 Key ideas

  1. useradd/adduser creates users; passwd sets passwords.
  2. Groups share permissions: usermod -aG developers asha.
  3. root is the superuser; use sudo for admin tasks.
  4. /etc/passwd lists users; /etc/shadow stores password hashes.
  5. Disable direct root SSH login.
💡 Real-life example: Users are employees, groups are departments, root is the managing director with every key.
rootSuperuser account
sudoRuns a command as another user (usually root)
GroupSet of users sharing permissions
/etc/shadowStores password hashes