This information concerns mainly the PCs with Linux used in the department.
To use the mathematics department computers you must have an account. One of the office staff can tell you how to do that. The first step is to fill out the new user application form.
When you get an account, you will be assigned a `username'. For example, it might be your first name arnie or your initials arw, or your first initial and your last name separated by the character `_', a_weber. In addition, you will be assigned a temporary password which will be some bizarre string of characters. One of the first things you should do is to change your password.
When you finish typing a line or command you must press the
In order to log on you must provide the computer your
username and password. At the login window first
type your login name, press the "enter" key, type your password and
press the "enter" key. As a security measure your password will not
appear on the screen. If everything goes OK the computer will start
an X session. Now you can use the mouse and start any of various
applications, or open a window (terminal). You can open a window by
placing the mouse arrow on the background and clicking the right
button (this opens a menu), then clicking in "New Terminal". Inside
the window you should see a `prompt' which may look something
like
The first thing you should do (while still logged on to the computer)
is to change your password to something secret which only you
know. Choose something no one else can easily guess but which is easy
for you to remember. It should be at least 7 or 8 characters. (It
can be longer but only the first 8 characters count.)
Your password should not be (a) in any dictionary, (b) a
place name, or (c) anyone's name or nickname. Also dates, street
addresses and license plate numbers are a bad idea. Punctuation
marks, digits, and even most control characters are allowed in
passwords. Capital letters are distinguished from lower case letters.
One possibility is to pick an easy to remember sentence and construct
a password from parts of that sentence. For example,
"SW&t7d's" stands for the phrase ``Snow White and the
seven dwarfs''.
You shall not use any passwords that you used in other places, like
the university NET-ID, or accounts on other universities (places).
To change your password, login on any public machine, i.e.,
poincare, and use the yppasswd command like this
The list of available printers at this moment are:
Additional information in the
Printing Guide.
In some cases the only way to fix the problem is by killing the
X-session. You may do that by typing <Ctrl-Backspace>. If that
does not work, type <Ctrl-F2>, which takes you to a non-graphic
screen, then <Crtl-Alt-Del> to reboot the machine. It that does
not work either, that is bad, it means that probably the only solution
is to push the reset button, or even to turn off and on the machine,
which often causes problems (it can damage the filesystem). Before
doing that it is a good idea to contact the system administrator just
in case he has some alternate solution.
Just as important as logging on is being able to log
off again, so that the terminal is secure and available for
someone else to use.
If you are using the Gnome desktop, open the menu of programs
and applications by clicking on the button with the gnome footprint,
select "Log out" and click "yes" in the confirmation window.
If you still can see the computer prompt that means that you
have not logged off completely. Type exit
or logout and you should see a login prompt
similar to this:
Note: Even if you have a "private" machine in your office
that nobody else is going to use, it is important that you
log off before you leave for the day or for a relatively
long period of time (hours). Do not leave programs
open and applications running unless really necessary.
Nightly backups are better performed on machines under low
activity (files cannot be properly backed up if the are modified
during the backup process.)
The machine will recover more easily after any temporary
server problems if nobody is logged on it.
You can
now type any of a large collection of system commands which allow you
to read mail, produce documents, etc. The system prompt may take some
other form, e.g., poincare%. In addition to reminding you
which computer you are using, prompts like this help you keep track of
what you are doing. Many programs have their own prompts. Thus when
you see the system prompt arnie@poincare$
you know it is OK to type system commands, but not
commands appropriate for some other program.
arnie@poincare$
Each time you are prompted, you type your old or new
password as requested. As is always the case with passwords,
nothing appears on the screen. That is why you are asked to retype
the new password to confirm that you got it right.
arnie@poincare$ yppasswd
Changing NIS account information for arnie on gauss.math.northwestern.edu.
Please enter old password:
Changing NIS password for arnie on gauss.math.northwestern.edu.
Please enter new password:
Please retype new password:
The NIS password has been changed on gauss.math.northwestern.edu.
What files are in your directory?: ls
To find out try
ls
Printing a file: lpr
prints the file named "weber" on one of the default printer.
Usually the default printer is the one in the computer lab (Lunt 215),
called lj2, but there are ways to change that default
for a given user. Also you can tell the print command to print on a
given printer with the -P flag, as in the
following command:
lpr weber
which prints the file "weber" on the basement printer, called
ljb.
lpr -Pljb weber
Rename a file: mv
changes the name of the file dumas to dean. Be careful! If a file
called dean already exists, this will destroy the old dean.
mv dumas dean
Copying a file: cp
makes a copy of the file mccoy and calls it duncan. Be careful! If
a file called duncan already exists, this will destroy the old duncan.
cp mccoy duncan
Removing a file: rm
removes the file ellis. Think twice! We do daily backups, so a
removed file may be retrievable, but don't count on it. If you need
to restore a lost file, inquire in the department office for the name
of someone who can help you.
rm ellis
Editing a file
There are various programs on different machines for editing files. A
popular one is emacs. A simpler one is vi, but it has
some disadvantages for new users - it has several "modes" and requires
some learning time before the user becomes acquainted to it. An
intermediate one is xedit. In any case you may use them by
typing in a window the name of the editor followed by the name of the
file to be edited, e.g.:
emacs myfile
Correcting a typing mistake.
To erase the last character you have typed use the <Delete> key or
the <Backspace> key. Probably only one of these will work, which one
depends on the terminal you are using. If you are unhappy with the one
that works it is possible to change it. To erase the entire line
typed so far press <Ctrl-u>.
What to do if you seem to be stuck and the keyboard doesn't
respond.
Well if that happens it is too late to read this, but here's what to
do anyway. Try the following: Press <Return>.
Press <Ctrl-c>; this
should stop whatever is going on and give you a new system prompt.
Press <Ctrl-q>; this unlocks the keyboard if it was accidentally
locked (<Ctrl-s> locks it).
How I do find out more about a UNIX command?: man
Use the man command. For instance, if you
want to know more about the lpr command,
type:
man lpr
The terminal is now ready for someone else to log on.
poincare login:
Comments: webmaster@math.northwestern.edu