u1

UNIX版本6的源代码

.sp
.SH
I.  GETTING STARTED
.SH
Logging In
.PP
Most of the details about logging in are in the manual
section
called
``How to Get Started''
(pages
.ul
iv-v
in the 5th Edition).
Here are a couple of extra warnings.
.PP
You must have a 
.UC UNIX
login name, which you can get from
whoever administers your system.
You also need to know the phone number.
.UC UNIX
is capable of dealing with a variety of terminals:
Terminet 300's; Execuport, TI and similar
portables;
video terminals; GSI's; and even the venerable
Teletype in its various forms.
But note:
.UC UNIX
will not handle IBM 2741 terminals
and their derivatives
(e.g., some Anderson-Jacobsons, Novar).
Furthermore,
.UC UNIX
is strongly oriented towards devices with 
.ul
lower case.
If your terminal produces only upper case (e.g., model 33 Teletype),
life will be so difficult that you should look for another
terminal.
.PP
Be sure to set the switches appropriately on your device:
speed (if it's variable) to 30 characters per second,
lower case,
full duplex, even parity, and any others
that local wisdom advises.
Establish a connection using whatever
magic is needed for your terminal.
.UC UNIX
should type ``login:'' at you.
If it types garbage, you may be at the wrong speed;
push the `break' or `interrupt' key once.
If that fails to produce a login message, consult a guru.
.PP
When you get a ``login:'' message,
type your
login name
.ul
in lower case.
Follow it by a 
.UC RETURN
if the terminal has one.
If a password is required,
you will be asked for it,
and (if possible)
printing will be turned off while you type it,
again followed by a
.UC RETURN.
(On M37 Teletypes always use
.UC NEWLINE
or
.UC LINEFEED
in place of
.UC RETURN ).
.PP
The culmination of your login efforts is a percent sign ``%''.
The percent sign means that 
.UC UNIX
is ready to accept commands from the terminal.
(You may also get a message of the day just before the
percent sign or a notification that you have mail.)
.SH
Typing Commands
.PP
Once you've seen the percent sign, you can type commands,
which are
requests that
.UC UNIX
do something.
Try typing
.B1
date
.B2
followed by 
.UC RETURN.
You should get back something like
.B1
Sun Sep 22 10:52:29 EDT 1974
.B2
Don't forget the
.UC RETURN
after the command,
or nothing will happen.
If you think you're being ignored,
type a
.UC RETURN ;
something should happen.
We won't show the carriage returns,
but they have to be there.
.PP
Another command you might try is
.C who ,
which tells you everyone who is currently logged in:
.B1
who
.B2
gives something like
.B1
pjp	ttyf	Sep 22 09:40
bwk	ttyg	Sep 22 09:48
mel	ttyh	Sep 22 09:58
.B2
The time is when the user logged in.
.PP
If you make a mistake typing the command name,
.UC UNIX
will tell you.
For example, if you type
.B1
whom
.B2
you will be told 
.B1
whom: not found
.B2
.SH
Strange Terminal Behavior
.PP
Sometimes you can get into a state
where your terminal acts strangely.
For example,
each letter may be typed twice,
or the
.UC RETURN
may not cause a line feed.
You can often fix this by logging out and logging back in.
Or you can read the description of the command
.C stty
in section I of the manual.
This will also tell you how to get intelligent treatment of
tab characters
(which are much used in
.UC UNIX )
if your terminal doesn't have tabs.
If it does have computer-settable tabs,
the command
.C tabs
will set the stops correctly for you.
.SH
Mistakes in Typing
.PP
If you make a typing mistake, and see it before the carriage return
has been typed,
there are two ways to recover.
The sharp-character ``#'' erases the last character typed;
in fact successive uses of ``#'' erase characters back to
the beginning of the line (but not beyond).
So if you type badly, you can correct as you go:
.B1
dd#atte##e
.B2
is the same as ``date''.
.PP
The at-sign ``@'' erases all of the characters
typed so far
on the current input line,
so if the line is irretrievably fouled up, type an ``@'' and start over
(on the same line!).
.PP
What if you must enter a sharp or at-sign
as part of the text?
If you precede either ``#'' or ``@'' by a backslash ``\\'',
it loses its erase meaning.
This implies that to erase a backslash,
you have to type two sharps or two at-signs.
The backslash is used extensively in
.UC UNIX
to indicate that the following character is in some way special.
.SH
Readahead
.PP
.UC UNIX
has full readahead,
which means that you can type as fast as you want,
whenever you want,
even when some command is typing at you.
If you type during output,
your input characters will appear intermixed with the output characters,
but they will be stored away by
.UC UNIX
and interpreted in the correct order.
So you can type two commands one after another without
waiting for the first to finish or even begin.
.SH
Stopping a Program
.PP
You can stop most programs by
typing the character ``DEL''
(perhaps called ``delete'' or ``rubout'' on your terminal).
There are exceptions, like the text editor,
where
.UC DEL
stops whatever the program is doing but leaves you in that program.
You can also just hang up the phone.
The ``interrupt'' or ``break'' key found on most terminals
has no effect.
.SH
Logging Out
.PP
The easiest way to log out is to hang up the phone.
You can also type
.B1
login name-of-new-user
.B2
and let someone else use the terminal you were on.
It is not sufficient just to turn off the terminal.
.UC UNIX
has no time-out mechanism, so you'll be
there forever unless you hang up.
.SH
Mail
.PP
When you log in, you may sometimes get the message
.B1
You have mail.
.B2
.UC UNIX
provides a postal system so you can send and receive letters
from other users of the system.
To read your mail,
issue the command
.B1
mail
.B2
Your mail will be printed, and then you will be asked
.B1
Save?
.B2
If you do want to save the mail, type
.ul 
y,
for ``yes'';
any other response means ``no''.
.PP
How do you send mail to someone else?
Suppose it is to go to ``joe'' (assuming ``joe'' is someone's login name).
The easiest way is this:
.B1
.ne 7
mail joe
.I
now type in the text of the letter
on as many lines as you like ...
after the last line of the letter
type the character ``control-d'',
that is, hold down ``control'' and type
a letter ``d''.
.B2
.R
And that's it.
The ``control-d'' sequence, usually called ``EOT'', is used throughout 
.UC UNIX
to mark the end of input from a terminal,
so you might as well get used to it.
.PP
There are other ways to send mail _
you can send a previously prepared letter,
and you can mail to a number of people all at once.
For more details see
.SE mail (I).
.PP
The notation
.SE mail (I)
means the command 
.C mail
in section (I)
of the
.ul
.UC UNIX
.ul
Programmer's Manual.
.SH
Writing to other users
.PP
At some point in your 
.UC UNIX 
career, out of the blue will come a message
like
.B1
Message from joe...
.B2
accompanied by a startling beep.
It means that Joe wants to talk to you,
but unless you take explicit action you won't be able to talk back.
To respond,
type the command
.B1
write joe
.B2
This establishes a two-way communication path.
Now whatever Joe types on his terminal will appear on yours
and vice versa.
The path is slow, rather like talking to the moon.
(If you are in the middle of something, you have to
get to a state where you can type a command.
Normally, whatever program you are running has to terminate or be terminated.
If you're editing, you can escape temporarily from the editor _
read the manual.)
.PP
A protocol is needed to keep what you type from getting
garbled up with what Joe types. 
Typically it's like this:
.B1
.fi
Joe types ``write smith'' and waits.
.br
Smith types ``write joe'' and waits.
.br
Joe now types his message
(as many lines as he likes).
When he's ready for a reply, he
signals it by typing (o), which
stands for ``over''.
.br
Now Smith types a reply, also
terminated by (o).
.br
This cycle repeats until
someone gets tired; he then
signals his intent to quit with
(o+o), for ``over
and out''.
.br
To terminate
the conversation, each side must
type a ``control-d'' character alone
on a line. (``Delete'' also works.)
When the other person types his ``control-d'',
you will get the message ``EOT'' on your terminal.
.B2
.PP
If you write to someone who isn't logged in,
or who doesn't want to be disturbed,
you'll be told.
If the target is logged in but doesn't answer
after a decent interval,
simply type ``control-d''.
.SH
On-line Manual
.PP
The 
.UC UNIX
Programmer's Manual
is typically kept on-line.
If you get stuck on something,
and can't find an expert to assist you,
you can print on your terminal some manual section that might help.
It's also useful for getting the most up-to-date
information on a command.
To print a manual section, type
``man section-name''.
Thus to read up on the 
.C who
command,
type
.B1
man who
.B2
If the section in question isn't in part I of the manual,
you have to give the section number as well, as in
.B1
man 6 chess
.B2
Of course you're out of luck if you can't remember the section name.