AUSAM/doc/intro.agsm/doc2

.SH "Getting your login name"
You will be given your login name during a
lecture.
The reason you all have different login names
is so that you can be working on something
of your own,
which nobody else can alter.
You have a completely different environment
from everybody else,
which means that other users cannot know exactly what you are doing
(unless they look over your shoulder).
Although the resources on a computer are large
they are not infinite,
and hence restrictions
are placed on every user so that the resources
are not depleted or congested.
These restrictions apply to such things
as the amount of space you can
use on disk,
and the number of processes you
can have going at any one time.
.H 2 "Logging In"
The first thing to do if you want to log in is find a terminal
that is apparently not being used.
The next thing to do is to ensure
that the terminal is turned on.
If it is not turned on,
turn it on and wait till the cursor\*F appears,
.FS
only on video or graphics terminals.
.FE
then hit <return>\*F
.FS
<return> denotes the 'carriage return' key on the keyboard.
It is marked as 'RETURN' or 'CR'.
The <return> is
.ul
very
important as the system will not obey you until you type <return>.
This applies in all situations.
.FE
until the system
responds.
If you are on a Tektronix terminal
remember to clear the screen (see section 1.4).
After hitting <return>
the system will respond
.DS

	login:

.DE
if nobody is using the terminal.
If this line does not appear then you must either wait
or find another terminal.
.P
When you have found a terminal with
.DS

	login:

.DE
displayed, just type in your login name followed by
<return>.
If the system responds with
.DS

	Who?

	login:

.DE
it means that either you typed in your login
name incorrectly or your login name is not known by the machine.
If this happens keep trying until you get a successful
login,
but if it continues to happen then 
consult the school's computer personnel.
Upon successful login the system will respond
.DS

	password:

.DE
.P
The machine is now waiting for you to type in
your password.
Anybody can find out
your login name, so,
in order to protect the privacy of
your files,
you have a password.
When typing your password you will notice that
the letters are not printed on the terminal.
This is to preserve the secrecy of your password.
.P
You can change your password and it is strongly
suggested that you do so
regularly; using one of at least
eight letters.
Changing your password will
be explained latter, in the section
"Common Commands".
.P
If you type in the wrong password the terminal
will respond with
.DS

	Wrong Password

	login:

.DE
and you have to start again with your
login name.
If you have correctly typed in
your password then the terminal might respond
.DS 1
~~~~~~System down twixt 17:00 and 21:00 tonite~~~~~~~~~~~<-- 1
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ianj

~~~~~~100 disk units~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<-- 2
~~~~~~~~4 processes
You have mail~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<-- 3
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<-- 4
.DE
.P
Message #1 is called the message of the day,
and is used by the system supervisor to tell users
of forthcoming events,
or just general information.
In this case it is a rather cryptic message saying that
the machine will be unavailable for use between
17:00 and 21:00 that night.
Don't be scared off by bad spelling or jargon words
as they are only used to keep the message short. If you
can't understand this message there are plenty of people
around to ask.
It is suggested that you take note
of this message as it may cause you some
inconvenience if you don't.
.P
Message #2 tells you of the
resources at your disposal. These will be explained
in greater detail later.
.P
Message #3 tells you that you have mail.
As in the outside world,
users of this system
can send each other mail.
This is a convenience
so that users can communicate without
ever seeing each other.
.P
The last message (the percent sign %)
is a way of telling you that the system is ready to take
commands.
This is usually called "the prompt".
The percent sign is printed by a
program called the "shell".
The shell is executed when you log on
and reads the commands you type
in.
It then performs the necessary actions
to execute the program.
It should be noticed that the shell does not care whether your command
makes sense. It merely passes your command to the particular program
that command uses.
.P
Once all of this has happened you are logged on to the
machine and are able to use its facilities.
.H 2 "Logging Off"
Logging off terminates
your session with the computer.
If you don't log off,
the system will automatically
log you off after
ten minutes have passed
since the last command was
completed\*F.
.FS
this should not be construed as an invitation to log off this way.
It only takes a few seconds for another user to (intentionally or not)
destroy all your files which may have taken months to prepare.
.FE
This is for your benefit
and for the protection of your
files as it prevents
misuse of your account
if you leave the terminal for
a long time.
.P
To log off you type
.DS

	[control]d

.DE
ie. you hold down the control
key and type a 'd'.
The control key (sometimes
labelled 'ctrl')
is similar in
operation to the shift key.
.H 2 "Line Editing"
Line editing is a way
of correcting typing errors in a line
before
the system reads them.
The system accepts each line only
after you have typed <return>.
.P
If you happen to make a mistake typing
anything in,
there are two ways to fix
the error.
.P
The first method of deleting errors is to
use the '#' character.
This character,
when typed after any other character,
will delete it from the line.
Thus several '#'s in a row will delete that
many characters back.
For example,
the following
.DS

	I are##m a fppl###oo;#l

.DE
will be read by the system as
.DS

	I am a fool

.DE
.P
To enter the character '#' you type '\\#'.
The '\\' (slosh) removes the special
meaning of '#'.
.P
As you can see in the above example,
using '#' to erase characters is quite
messy,
making the line rather hard to
read on first glance.
If you are using a video terminal
(a terminal with a screen)
you can use a backspace key instead,
so that when you make a mistake
in typing you can simply
use the backspace key to correct the errors,
and then continue typing.
To change the erase character
to a backspace you must type
.DS

	% set
	%

.DE
After typing in 'set',
experiment with using the backspace key
to erase characters.
As you backspace over the characters
they will disappear,
indicating that they have been deleted.
.P
If you are on a DECwriter terminal,
typing 'set' will not cause the
erase character to be changed.
This is because it is not
considered useful as the terminal
will only overprint the characters.
If you are on a tektronix terminal
and you type in 'set',
you may find it difficult to find
the backspace key.
In fact it doesn't have one!
You must use [control]h.
([control]h is the character sent to the
computer by the backspace key).
.P
The second form of "line editing" is the '@' sign.
When '@' is typed,
all of the characters typed on the line so far
will be erased.
If you type an '@' in error,
it may be erased
(like other characters)
by a '#'
(or a backspace as the case may be).
For example,
the following
.DS

	I qte@I arm not sil@I am no fool

.DE
will be read be the system as
.DS

	I am no fool

.DE
.H 2 "Reading Your Mail"
To read your mail type
.DS

	% mail

.DE
and the following may appear
.DS

	From root Fri Nov 13:05:44

	Welcome to UNIX and AGSM
	We hope your stay here is enjoyable

	Save?

.DE
.P
The computer is now waiting for you to type
.DS

	yes   OR
	no

.DE
depending on whether or
not you want to save the mail.
If you save your mail it is added to a file
called "mbox".
.P
If you wish to send mail to another user
whose login name is 'joe' (say),
you type
.DS

	% mail joe

.DE
Once you have done this the system
is waiting for you to type in the mail.
You might like to type
.DS

	I've finally arrived......

	Must talk with you about that
	discussion we were having.

			Jack

.DE
When
you have finished your mail
you must now type
.DS

	[control]d

.DE
ie. hold down the control key
and type a 'd'.
When 'joe' logs on next he will be told that
he has mail,
and when he reads his mail the date and
your login name will appear on the front
of the mail sent by you.
.H 2 "Error Handling"
From time to time unexpected messages
will appear on the terminal
probably
informing you that an error
has occured.
Ignore these messages at your own peril!
Don't be tempted to sit there like a stunned mullet;
go and ask somebody what the message(s) mean.
It has been distressingly observed
in the past that
people have seen an error message,
ignored it,
and then found out two days later
that the work they had been typing in
was lost forever.
It is very
frustrating for the computer personnel
who are asked to fix up such
problems,
when told they occured
days earlier,
and could have been avoided.
It is also frustrating for you
as it may be too late to do
anything!
Hence it is very important that
you don't ignore potential error
messages.
.P
If you are not sure what the error
is or what caused
it,
ask somebody.
Most errors can be corrected
by any user familiar with
the system.
For the rest,
contact the system staff
(in this case write the error message down).
Lost files
can normally be recovered.
In this case, the system staff
.ul
must
be informed and given the name of the file and the date that it was last
changed (not used, but altered)\*F.
.FS
if you cannot notify them personally, use the mail command viz "mail root".
.FE
.H 2 "Stopping Programs"
If at any stage you wish to stop
a program you hit the
delete key
(labelled "del" or "rubout").
Some programs,
like the editor,
will not stop execution when
you hit this key but, instead, return control to you.
.H 2 "System Crashes"
From time to time the "system crashes".
This means that the system
(which is just a program)
has either developed a fault,
or it has found a fault in the
computer
(usually temporary).
When the system crashes nobody can
use it,
it will become lifeless.
No characters will be printed on
terminals,
all programs will stop.
During violent thunder storms
the system will be stopped
to prevent any damage to the
computer and related
hardware.
If the system crashes while you were
in the editor,
all information after the last
write will be lost
(the editor is explained in later sections).
In some rare circumstances you will be
able to recover the lost information.
If this happens you should
try and find the system staff who
will normally be in Rm 411 recovering the system.