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  1. On a unix system, ordinary users will get the message "Permission Denied" if they try to perform tasks such as adding/deleting other users, adding/deleting programs in /usr/bin or backing up all files in the directory /var/spool/mail . Tasks such as these are system administration/maintenance tasks. To perform the tasks that can only be done without the restrictions that apply to normal user accounts, the administrator must use the superuser account.
  2. The superuser account has the uid 0 and normally uses the username root . This account is not restricted by any of the permissions or constraints that apply to a normal user account. This allows the superuser account to perform the required system maintenance activities. But the lack of restrictions also means that the superuser account has none of the usual safeguards and must be used with care; unix legends are full of stories of administrators logged in as root who typed " rm -rf / " and deleted the entire filesystem.
  3. There are 2 ways that you can become root:
    1. login as root (on Floppix all passwords are the same so the root password is the same as your normal user password).
    2. login using your normal user account and then enter the command: su -
      The su command (substitute user) allows you to take on another user identity; if su is entered without specifying a username, it allows you to become superuser (assuming that you have the superuser password).
  4. Method 2 is preferable for 2 reasons:
    1. If you are already logged in, you are more likely to exit from the superuser account back to your own account when you are finished the administration activities. When you are using your own account, a mistake will not bring the entire system down.
    2. If you su to the superuser account, a log entry shows the time, date and username of the person who su'd to root.


  1. Login using your own account.
  2. Try to delete the file /etc/passwd . What message do you get?
  3. Use the su command to become root.
  4. Check the log and find the entry for the su command. ( on Floppix, the system logs are directed to /dev/tty8 ; press [alt][F8] to see the logs; [alt][F1] to return to console 1)
  5. What is the output from each of the following commands?
  7. If you are working on floppix, delete the file /etc/passwd .
  8. Logout.
  9. Now:

Copyright © L.M.MacEwan
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