AUSAM/doc/intro.agsm/doc5

.SH "Communicating With Other Users"
.P
There are several ways in which
users can "talk" to other users.
One way (write) corresponds to making a telephone call and the other
(mail) corresponds to mailing a letter.
.H 2 "Mailing A User"
The process of mailing somebody
has been explained earlier,
but here is a short rundown
on the procedure.
To mail a user you type
.DS

	% mail [login-name]

.DE
followed by all of the mail you
want sent.
To finish sending the mail
you must type
.DS

	[control]d

.DE
ie. hold down the control key and type a 'd'.
In general [control]d is the way that
you indicate to most programs that
you have no more data for them.
You can 'mail' a user regardless
of whether he/she is logged on.
.H 2 "Writing To Another User"
Writing to a user is a very convenient
way of having a conversation with
another user
'cu
who is logged in.
To write to a user 'joe' type
.DS

	% write joe

.DE
If the user is not logged in
the system will tell you so and the terminal
will respond
.DS

	joe not logged in
	%

.DE
You can't write to someone unless he is logged
in.
You may also receive the message
.DS

	permission denied
	%

.DE
This means that joe is logged in but that he doesn't want to be
interrupted.
This can be done via the command 'mesg'.
The command
.DS

	% mesg n
	was y
	%

.DE
means that nobody can write to you now.
The 'was y' comes from 'mesg' and reminds you of your previous status.
You can change your mind by typing 'mesg y' or just 'mesg'.
\&'mesg' by itself changes from either 'y' or 'n' to 'n' or 'y' respectively.
.P
If the user were logged on,
then he would receive the message
.DS

	Message from [your-login-name]...

.DE
When writing to someone it is
usual to wait for his reply,
before you start talking to him.
.P
After you have typed in
.DS

	% write joe

.DE
everything that you now type
will also appear on his terminal.
As an example the following may happen
(lines in capitals are generated by the
other user)
.DS

	% write joe

	Message from joe....		('joe' has just written back)

	have you still got that book on Accounting,
	or did you take it back to the library????????

	I WAS JUST ON MY WAY TO THE LIBRARY NOW
	TO RETURN IT.

	well don't run off with it, I need it
	for an assignment.

	OK, WILL DO

	thanks.

.DE
Now that you have finished the conversation
you type
.DS

	[control]d

.DE
and the terminal will respond,
as usual
.DS

	%

.DE
and 'joe' will receive
.DS

	EOT

.DE
When 'joe' types in a [control]d you will
receive
.DS

	EOT

.DE
as well.
The EOT indicates
that the user writing to
you has finished talking with you.
.H 2 "Who is 'root'"
\&'root' is the name of a rather
special user of the system.
This user has powers and abilities
far beyond those of mortal men\*F.
.FS
have
.ul
you
seen the movie?
.FE
Nothing you can do can
ever stop 'root' being able to read
or write on
your files.
The mode on any file or directory is totally
ignored
whenever 'root' wishes to
access anything.
As well as ignoring modes on files,
\$'root' has the ability to change
your password,
which can be handy if you forget it!
.P
Like Superman, 'root' is generally friendly and uses his powers for good.
\&'root' allocates new accounts, initiates the backup copying of files
on week nights.
.P
In reality, the system staff use 'root'\*F to perform their duties.
.FS
although they, like him, have apparently super\-normal abilities.
.FE
Thus messages and mail of a system nature (hardware or other such problems)
should be directed to 'root'.
The name 'root' comes from the fact
that he is the root of the system.