Chapter 3

3.1 Introduction

DEMIGOD

In UNIX the superuser is the only user to have power to perform all priviledged tasks.

 

3.2 The UNIX Model of Ownership

Ownership of Files

Ownership of Processes

3.3 The Superuser

UID of zero

a.k.a. root

may perform any valid op on a file or process

may execute some system calls

may change ownership credentials at will

login program

3.4 Choosing a Root Password

should not be easily guessed or discovered

random sequence of letters, punctuation, & digits

case sensitive

only first eight characters are significant

change password too

3.5 Becoming Root

may login as root

"su" to root

"su username" as root to get to an account

must be in "wheel" group

sudo: A limited su

3.6 Other Important Users

root is only user with special status

some nonhuman logins for special purposes