newbie: Getting Started
date: 8.1.99

Getting started with Unix

Unix is a multiple user operating system. This means that it is designed to
allow several people use the machine at the same time. Unlike some operating 
systems, when users are accessing it, they have the potential to access and use
all parts of the system, even while not sitting at the actual computer.

To distinguish users, each person has a 'User ID' (User Identification or UID) that
tells the system who is accessing it at a given time. This User ID is a number
between 0 and 65535 and gives the machine a way to remember each user and
act accordingly. To us, these numbers are awkward and difficult to remember,
so us non computers use login names. These login names are eight character 
alphanumeric IDs, typically in a format that represents names, company employee 
ID or nickname. "jericho", "bmartin" and "abcd0005" are all valid login names
that you might find on a system. 

Each UID is associated with a login name. For example, on this system the user
'jericho' has a UID of 1000. During system use, I will see most everything
referred to as 'jericho', while the system is really tracking everything with
the numeric ID.

To access your account on a unix box, you must first login to the system.
This can be accomplished by sitting down at the system console (physical access),
or connecting via a utility/protocol such as telnet, SSH, or FTP. For the
purpose of our lessons, we will assume you are logging in to your own system
at console.

Most unix systems will greet you with something like this:


forced login:


This is telling you that the machine's name is 'forced', and that it is
awaiting user login. At this prompt you type in the name of the super user
account (root), or the name of your user account. Upon entering your login
name, the system will then challenge you with:


forced login: jericho
Password: 


[If this is your first time logging in to a newly installed Unix system,
 it is advised you immediately create a new account for you to expiriment
 with. For Linux and FreeBSD, this can most likely be accomplished by
 running 'adduser' and following the detailed prompts. We will get into
 adding additional users in more detail later.]

At this point, type in the password you previously selected to protect
your account. If this is the first time you are logging into a new system,
it is likely there is no password set. If this is the case, simply hit
the ENTER key. Note: You will not see the password as you type it in!
This is done for security reasons, so that anyone looking on will not
be able to easily see your password.

When you successfully input your password, the system will log you in. 
On many commercial unix flavors, you will simply be dumped to the command 
prompt. On more user friendly flavors, it may display where you logged 
in from last, a system message, notify you of new mail, and more.

When all is said and done, this is an example of what you will see:


forced login: jericho
Password: 

Last login: Sat Jul 31 15:51:41 1999 from testing.attrition

          F  O  R  C  E  D  .  A  T  T  R  I  T  I  O  N  .  O  R  G
      ----------------------------------------------------------------------
        This computer is privately owned and  operated and  is in  support 
        of ongoing public and semi-public activities.   If  you   are  not 
        authorized to access or  use this system, disconnect now. Users of  
        this  system have  no  expectation of  privacy. Logging in denotes 
        consent to monitoring by  ATTRITION.ORG  staff or whoever owns us.
      ----------------------------------------------------------------------

You have mail.
 
forced ~$ 


At this point, the "forced ~$" tells you that you are logged into a machine
called 'forced'. The $ prompt represents a user level account and prompt,
indicating the system is ready to accept your commands. This is also known
as the 'command prompt'.

[Warning: The 'root' account is the most powerful account on a unix box.
 This account should not be used for day to day activity. While using this
 account, there are very few controls that will stop you from potentially doing
 damage to your system. Deleting files and destroying information is likely
 to be permanant.]

We will get into passwords much more in depth with another lesson.


jericho@attrition.org
(c) copyright 1998, 1999 Brian Martin