Serving Your GuestsTOC
The butterfly's day
hath not long to tarry
for the spider doth pray
for to prey, yea very
What is the UNIX Philosophy?TOC
One might say that the era of open friendly computer
systems was born with UNIX. One would be wrong to say so,... yet
there is more than a little bit of truth in the saying. There is
probably no question that the World-Wide Web is the child of the
UNIX philosophy. One of the major components of the UNIX operating
system is the open nature of the filing system: the ease with which
files can be shared as well as the ability to keep some files
locked up and away from prying eyes. Many persons use UNIX
without any knowledge of these capabilities. The typical user may
find themselves using a UNIX server without any idea that the
system is not dedicated to their own individual needs. The beauty
of UNIX is that a user might feel this way. The truth is that the
system has many features which are definite clues to the multi-user
facilities of UNIX. In most cases, your UNIX server will not
provide you with a convenient word processor. The reasons for this
are many: - The system has many different printing ports.
- The UNIX server has many different terminal types
accessing it at the same time. Consequently, it is best for the
UNIX server to only transfer ASCII-type file information back and
forth between the server and your computer.
- The UNIX
server has many different clients. Each client uses some of the
computing time. The more time spent with each client, sending
special graphics files for example, the more time you will have to
wait to be served.
Perhaps the major reason that
there are not convenient word processors on UNIX machines is that,
up until recently, UNIX machines were mostly used by computer
enthusiasts with a great deal of patience. There are some ways to
get around the lack of easy-to-use editors. One is to use your
browser's e-mail capabilities to send files to your email account.
Then save the files and strip the headers. That is: strip the
address and subject e-mail information. Another way is to edit on
your personal computer and the transfer files using an
ftp utility. Finally, if you are a patient person you can
learn to use vi. This chapter is mainly for those
who have neither the time nor the inclination to buy a UNIX or vi
manual in order to learn all the right stuff.
What is a Server?TOC
A server is to the computer network like the heart to the body. A
server is a computer which is primarily dedicated to storing and
distributing files, and running computer applications over a
network. The advantage of using a computer application from a
server is readily apparent to anyone who has tried to keep the
software in a local network up-to-date. It is a tedious and
thankless job to go from one machine to another installing the same
software. If the software is accessed over a network, then it
requires only one installation. This is a great time saver.
Once a file or program is installed on the server, anyone with the
proper authority can access the information or program. Whenever
you access a distant webpage you are using a server, or perhaps a
series of servers. Using a server is a little like going to eat
at a restaurant. If the restaurant is busy, you must wait in line.
This is called a queue in computer lingo. Finally, you are seated.
The server awaits your request. Over a network, you make a request
by moving your mouse or striking your keyboard. The request is
then written down on a pad of paper by your server (or put another
way, the computer stores your request in a buffer). The server
then takes your order into the kitchen for processing.
Sometimes the restaurant is very busy. The server may not be able
to attend to your requests quickly. This can also happen with
computer servers. You may find yourself typing into your server,
while at the same time nothing appears on the screen. This can also
happen on your personal computer, if it is doing several tasks at
once. We imagine that when we type something at the keyboard,
there is a direct link from the keyboard to the screen: just like a
mechanical typewriter. This is not the case. Whenever you type on
the keyboard, the information goes to a buffer. This is a
temporary storage mechanism. The information in the buffer is then
processed by the computer, usually as letters printed on your
screen, or by the movement of the arrow on your screen. If the
server is busy, or if you have a low priority in the computer
queueing system, then your request is not processed immediately and
you must wait for your action to appear on the screen. If you are
editing a document over the network, then each time you press a key
on the keyboard, you are requesting a service. The keyboard request
travels across the network to the server which then recognizes the
request and sends a signal back to your computer. Your computer
processes the signal and then puts the letters on your screen. This
process is called echoing. On most servers, the more requests
you make, the quicker the server responds ... up to a point. If you
leave your editing process for a short time, you may notice that
when you return, you can type several letters before the server
will echo the letters back to your screen.
A
Note on BuffersTOC
A buffer is a temporary data storage system: a kind of holding
tank. The most efficient transfer of data is in bundles. Suppose
you are typing at a UNIX prompt. The letters you
type are placed in a buffer and echoed back to your screen. The
command you type is not executed until you hit the "
enter"
key. The use of buffers makes multi-tasking over
networks more efficient. A Note on The Enter
KeystrokeTOC To avoid
confusion, I will use the symbol "¬ " throughout, to denote the
enter keystroke.
What is a Client? TOC
A client is the person, or computer system,
making a request from the server. The use of the term client is to
indicate the relationship between the two computers in a given
interaction. The client is dependent on the server for obtaining
the resources needed and for carrying out some operations.
Operations that are server-side require the server to do most of
the work. The client simply receives the results of the work.
Editing documents using an editor like vi is
primarily a server-side relation. Operations that are
client-side require the personal computer to obtain information
from the server, and then perform the task of making that
information usable. The concept of the World-Wide Web involves
participation by the server and the client. The use of a browser
is primarily a client-side relation. This does not minimize the
importance of the server in the interaction. The future of
client/server computing lies in client-side applications which make
UNIX invisible. This does not mean that the UNIX system will not be
used, it only means that the average person will be unaware of how
they are using UNIX and telnet commands. A good
example of this kind of distributed computing is the World-Wide Web
browser. Another example is afforded by transparent
ftp programs. These ftp programs will be
discussed later in the chapter.
Using the
Directory SystemTOC
Most directory systems have a parent/child relationship. In
this sense, the directories on the machine, and in particular on
your account, are like a family tree. When you log onto your UNIX
account the computer places you in your HOME
directory. On a UNIX machine you can always go
HOME by entering $ cd home ¬
where $ represents the UNIX prompt sign and
where cd means change directory. Starting in
any directory, and assuming that you have the system's permission,
you can move to the parent directory by entering
$ cd .. ¬
This means change directory and go to the directory
which contains my current working directory. You can create a
directory in your HOME directory, simply by
entering $ mkdir www ¬
This action will create a child-like-directory,
in your HOME directory, called "www"
A child-like-directory is usually called a
subdirectory. This simply means a directory which lies
below on the family tree of the directories.
To see a list
of directories and files enter at the prompt: $
ls -a ¬
This action will list all files and directories along with their
characteristics. Another way to list is $ ls
-l ¬
which lists everything
along with their characteristics except the hidden files . If
you get lost wandering through your directories, enter
$ pwd ¬
at the prompt to print your working directory. Remember,
on UNIX, unlike real life, you can always go home.
Setting Up a Homepage on Your ServerTOC
The most common UNIX
editor is vi for "visual."
This visual
editor is not impressive to those who are used to personal computer
editors. But when it was introduced in the late 1970's, by Bill Joy
at the University of California-Berkeley, it was quite an
improvement over the mainframe editors of the day. If you are used
to editing documents on a personal computer you may find the use of
vi a strain. I find that after using vi, and then switching to a
personal computer editor, that I am constantly typing vi editing
commands into my documents. Though I use vi, I would not recommend
it for general editing use. Instead, I have developed some
procedures for editing on your personal computer and doing some
very simple work with vi or another editor. One other popular
editor is Pico We will discuss some point about
these editors later. If you are interested in using a UNIX editor,
I would suggest buying a reference book.
The
Transparent ftp SolutionTOC
In order to use an ftp program you must have
a direct IP, that is a an internet protocol,
hookup for the internet or be using a SLIP or
PPP connection. These connection provide the
correct coding systems for the secure transfer of your files. The
good news is that there are now several Windows/Macintosh products
on the market which do ftp in a user friendly
environment. These products are very transparent, but there are too
many possibilities to discuss them all. Remember to set the file
transfer to binary, especially if you want to move graphics files.
These ftp products will sometimes add
extraneous characters to your files, but even if they do, they
extra characters do not interfer with how your browser reads the
HTML or graphics files. Two such products which I have used and
can recommend are: WS\_FTP for the
IBM-compatibles at
http://www.csrs.net/junodj/ws_ftp.htm
Fetch for the Mac at
ftp://ftp.dartmouth.edu/pub/mac/
For information on Fetch see:
http://labweb.soemadison.wisc.edu/lab/pages/classes/moving_mac.html
If you have a nice ftp program
running on your personal computer, such as Fetch
or WS\_FTP, you may find it much easier to use
than an e-mail system. The ftp program will do
all the work and it will move In-line image files correctly
provided that you enable, or check, the binary box on your ftp
program.
The Command Line ftp SolutionTOC
If you are using
command line telecommunications package or if you are using a
command line interface to move files from one UNIX server to
another UNIX server then enter at the UNIX or DOS prompt:
C:$\backslash$> ftp open *server-address ¬
where *server-address represents the telnet
address location of the server you wish to use. If you have an
account on the server you will be prompted to enter your account
information. You should then receive an ftp
prompt: ftp> If you wish to send, or
receive, an In-line image you must enter at the prompt:
ftp> bin ¬ for binary. You should
receive a response of the type: ftp> bin 200 Type set to
I ftp>
To return to text transmissions enter at the
prompt: ftp> ascii ¬ which
should elicit the response: ftp> ascii 200 Type set to A
ftp>
To exit, enter at the prompt:
ftp> quit ¬ If you want to send a file to
the server, make sure that you begin your ftp
session in the correct subdirectory on your personal computer. You
may move through directories on the server by using the usual
commands. Be aware that in an ftp session, you
may not have the same permission to move around on the server as
you would in a normal session. As an example, go to the projects
directory, on your computer, holding the project files for this
book. Enter at the DOS prompt:
A:$\backslash$Webbing$\backslash$Projects> ftp ¬
Log on to your account as usual.
Let us move to our www subdirectory:
ftp>cd www ¬ To put your documents on the
server use the put command:
ftp>put simple.htm ¬ To move In-line images change
the Type to binary: ftp>
bin ¬ Once again use put:
ftp>put sample.gif ¬ When you are only
moving a few files this method works very well. To move more files
you can do multiple commands, like mput. Also you
may wish to move files to your local computer to edit. To do this
simply use the command get:
ftp>get simple.htm ¬ This command will place the
file on the directory of record when you began your session. To
use DOS commands on your personal computer while in the program
ftp use the following form
ftp>!dir /w ¬
This will print the window form of your DOS directory
file command.
A Note About E-mail SolutionsTOC A standard
e-mail solution will only allow you to move
ASCII- type files securely. To move In-line images to your
server, you will need to use one of the following: -
ftp if you have a SLIP or PPP connection.
- kermit or zmodem if you
have only a simple modem connection.
-
MIME attachment feature on your e-mail program.
One possibility is to encode the file and move them to the UNIX
server using e-mail and then decode the file. This sort of
manuvering requires some ingenuity. Postscript files are
ASCII files. But even if you can move your graphics files
using Postscript, you will need to use a file converter on the UNIX
machine.
The Pine E-Mail SolutionTOC The easiest way to
transport your files may simply be by using the attachment feature
of your personal computer's e-mail program. You may attach a
variety of files types using this feature. Files can be handled by
these e-mail systems using a MIME coding scheme and transported so
that the actual file is attached and
sent to
your e-mail account on your UNIX server.
If you wish to transfer graphics files or other binary files,
be aware that you will not wish to read the e-mail,
but rather save the attachment file
as a file on the UNIX server.
Many World-Wide Web browsers have e-mail programs that are
designed to transfer attached files.
Open your favorite e-mail program, in my case, I have used the
Netscape e-mail program.
\input fneml.tex
Click on the "Send Mail"
or "To:Mail" hot button.
A new message editing window should appear. Send the email message
to your e-mail account on your UNIX server. You may use the
attachment feature of your e-mail program to attach files other
than text files. For instance, you can attach graphics files using
this feature. You can also attach your html files which you can
then save using the e-mail account on your server. When you do
this it is important to make sure that your personal computer mail
program does not download and erase the files from your server. In
some cases, this may simply mean that you must act quickly before
your e-mail program automatically moves the message from your
server account to your personal computer. You should be aware that
this could be a problem.
\input fattch.tex
Now "click" on the "Attach File"
hot button and use the dialog box to browse for the file you
wish to attach.
\input fgif.tex
For this example, I have found the file info.gif
in the Projects folder. If you "double click\rq
\rq
on the file or use the appropriate hot
button the file will be loaded into the "Attachments"
dialog box.
If you will be using this feature of your e-mail to move
files, then you may wish to disable the automatic e-mail download
feature. This will mean that you will need to manually download
your e-mail periodically. On the other hand, provided that you
are careful to quickly access your server account and save your
files you should be able to leave your automatic e-mail download
feature enabled. This assumes that your e-mail program deletes the
server-side mail messages when it downloads them to your personal
computer. If it does not delete the files, then you should be able
to access your files on both machines without changing any
automatic settings. In addition to mailing files to yourself,
you may wish to mail or recieve files from others. If someone sends
an e-mail message with a file attached, you should be able to
access it on both your server and your personal computer. If your
e-mail program deletes meesages when it downloads them, then simply
forward the message back to your UNIX account and quickly save it.
You may also send files to other teachers and friends using the
attachment feature.
\vfill
\eject
Now "click " on the "OK"
hot button to attach the file to your e-mail
letter. As you can see, the file
info.gif has now been added to the "Attachment"
list for my e-mail message.
\input fsend.tex
When you send this e-mail message, the e-mail program will send
this file using a MIME or Multipurpose Internet Mail Extension.
I now turn to the second part of the process of moving the file.
Our graphics file has been sent, now we must go and pick it up. I
wish save the files on the UNIX server machine using the
Pine e-mail program. This is a common e-mail utility on
UNIX machines. If Pine is not available on your
UNIX server you should request that it be made available. It is
particularly important for those wishing to make use of attachment
files.
Pine is a product of the University of Washington and
does a great job with MIME. You should be able to start
Pine by entering at the UNIX prompt: $
pine ¬
\input fpinea.tex
Now enter "I" to open the index folder to view the list of
messages in Pine. You may wish to explore
some of the other features of Pine. Using a UNIX
e-mail utility like Pine can be more difficult
than the usual personal computer e-mail program, however, there are
some advantages. When you use an e-mail package on your server, it
allows for more security and privacy. Downloading your messages
to your personal comuter will often make them available to anyone
using your computer. When you leave your messages on your server,
you only have one set of messages to organize and only one mailroom
to keep uncluttered.
\input fpineb.tex
I wish to select the e-mail message infogif in
this list. This is labeled as message number 44 in my list. This is
the message I have just sent along with an attached file. Enter the
number or use the curser keys to move to the line and hit the
"Enter" key on your keyboard.
It may be necessary to use the "O" command to see all the
possible Pine commands. In fact, you should
choose the "V" command to save the graphics file. Note that the
pine editor gives special instructions since it has already
recognized the file as a "gif\rq
\rq image file.
\input fpinec.tex
Now you may use the usual save command and Pine
will ask you if you wish to save the file with the original name.
In some cases you may wish to change the name. The name should not
repeat the name of a file in your home directory. If you think this
will be a problem, give the file a different name before you mail
it.
\input fpined.tex
We have chosen to save and we are given a final menu option. Return
to accept and save as info.gif
or
^C to cancel. You may also use
^G
to give a different name or path.
\input fpinee.tex
While we have chosen to move a graphics file using the Netscape
e-mail program, keep in mind that it is possible to move text files
as well.
The Browser E-mail/vi SolutionTOC
Step 1 Construct your webpage using an ASCII text editor
on your personal computer. When you have constructed a webpage use
the "open local document"
feature of your browser to preview your webpage
document. Step 2 See the section on
"Setting up E-Mail". Copy or attach your document into an e-mail
message which you then mail to yourself at your e-mail account on
your server. One way to do this is to use the browsers e-mail
facilities. If your browser has been initialized correctly, you
will enter your password to access your server account. By using
the browser e-mail facilities, you are then able to write your
document, or paste it into the e-mail message using a nicer editor
than would be available on your server.
Step 3 If you have your
e-mail deleted from the server account when it is downloaded to
your personal computer, then you will have to act quickly to save
the e-mail document into a file on your server. Have your UNIX
e-mail account up and running. Do this by logging into your e-mail
from your "www" subdirectory. If you do this you can then save you
e-mail message to a file in the "www"
subdirectory.
Step 4 Save the e-mail self addressed
file to a file name of your choosing. If it is intended to be your
homepage it should look like
welcome.html ¬
where ¬ represents the
"enter" key on your keyboard. Otherwise, enter
*.html ¬ where *
represents any name of your choosing. Exit your server e-mail
program
Step 5 Enter the following
at the UNIX prompt:
$ vi *.html ¬
where once again the "*" represents the file
name that you used for the e-mail message. In other words, you
should not actually enter an asterisk at the prompt.
Step 6 Now strip the unnecessary e-mail
information carefully by typing "dd",
that is delete one line, until you have reached
the beginning tag <HTML>. If you are really adventurous you may
delete all the header lines at once: that is type "16dd", for
example. If you do this, you may want to make sure that you have
plenty of space above your first HTML tag.
Step 7 You may now save the file by
entering, precisely:
:wq ¬
Step 8 Enter the following at the UNIX
prompt: $ chmod o+r *.html ¬
Your file should now be ready to access over the World-Wide Web.
\input fpico.tex
A Note on the Pico EditorTOC
The pico editor is available on many
UNIX machines and is gaining in popularity. If
you have used the pine e-mail system, then you
were probably using the pico editor. Using pico
has the advantage of always being able to see useful commands. You
may also use help to see a list of other commands.
Step 5/pico Enter the following at the
UNIX prompt:
$ pico *.html ¬
where once again the "*" represents the
file name that you used for the e-mail message.
Step 6/pico Now strip the unnecessary e-mail
header information by typing "control k",
which appears on the screen labeled ^K.
This will delete one line at a time. Continue until you have
reached the beginning tag <HTML>.
Step
7/pico You may now save the file by typing "control X" and
then answering yes to the save buffer enquiry. You must now make
sure that the file is readable by others.
Step 8/pico Enter the following at the UNIX prompt:
$ chmod o+r *.html ¬
Your file should now be ready to access over the World-Wide Web.
The Browser E-mail/sed SolutionTOC
The UNIX utility sed is a stream
editor, meaning that you can edit documents by using a sequence of
commands. You might think that this would be inferior to using a
visual editor, but that is not always the case. If you know exactly
what you want to do, sed can be extremely helpful
and certainly less confusing than vi.
Step 1 - 2 Follow the directions in the
previous section "The E-mail/vi Solution"
Step 3 As an example of a different way of
saving files from email, log onto your UNIX account and start your
UNIX e-mail from your HOME directory. You may
save to different subdirectories by giving the correct path to the
subdirectory. Save the e-mail self addressed file to a file name:
www/strippit.html Exit your server
e-mail program. Step 4 Enter at the UNIX
prompt: $ cd www ¬ This should
move you back into the "www"
subdirectory. Now enter at the prompt:
$ sed '1,16 d' strippit.html >
stripped.html ¬
making sure to place a space between the 16 and the "
d." This simple command will strip 16 lines from the file
strippit.html and write the result in a new file
stripped.html. Once again, since you saved the file
from e-mail the UNIX system will likely assume that it is a private
file and will not let others access the file. Consequently you
must finnish by entering at the prompt: $ chmod
o+r stripped.html ¬ You must use a different name for
the stripped file each time you do this,
since sed will not rewrite files. Also, if you attempt to save
your e-mail to the same file it will append or add the e-mail to
the file. So use a different file name each time, or delete the
file "strippit.html" after stripping it by entering
at the prompt: $ rm strippit.html ¬
each time.
Using a ModemTOC
Using a modem for accessing your server is almost always less than
ideal. Due to budgeting in education, the use of modems in the
classroom is the norm. Even if the baud rate, or modem speed, is
high, the transmission channels are less secure and require better
error correcting codes. Recently, great strides have been made to
improve the speed of modems. The only problem is: getting software
to use on your system which makes the modem "transparent."
If the modem is not invisible, it is by definition
a problem. There are several good products on the market, but
there are far too many to discuss them individually. If your school
system is paying good money for a commercial product, then the
seller should give you as much support as you need to access your
server properly. Call the provider and don't be shy. Most
teachers and school districts work with limited budgets and so
freeware and shareware become the solutions of necessity, not
choice. Most UNIX machines should be running "C-Kermit" and
"xmodem." The xmodem software is common on
Macintosh systems and should allow you to transfer files via modem.
The kermit is freeware developed at MIT and is
available for both the Macintosh and the Windows/DOS platform.
For example, suppose you have a Microsoft Windows Terminal
program running over a modem. On my home computer, I have Windows
3.11 with kermit as an option in the Windows
Terminal program.
The Kermit SolutionTOC
Kermit is a software package developed over several platforms that
allows the transfer of files over modems. You should always use
kermit in the binary mode. Step 1 Go to the
www subdirectory on your UNIX account and enter
at the prompt:
$ kermit You should see something like the
following: Step
2 Pull down the "Transfers"
menu and select
"Send Binary File. " o Browse through your system until you are in
the correct directory for sending the file. Then click on the
cancel button. This aligns your system so that you can quickly
send files. If you want to explore the full range of
kermit commands enter a "?"
Step 3 Enter "receive"
at the kermit prompt and you will receive
the response to return and send C-Kermit>receive Escape
back to your local system and give a SEND command... C-Kermit>
Step 4 now return to the "
Transfers"
pull down
menu and once again select "Send Binary File "
or
"Send Text File." Click on the file you wish to send and the
terminal program will do the rest.
The Modem
Paste SolutionTOC
To
use this method you must have a pasting facility in your
modem/window.
Step 1 Dial in
and log onto your account.
Step 2 Open a file using your favorite
UNIX editor, say vi
$ vi
anything.html ¬
\input fmyservi.tex
and immediately type "i." The difference between my use
of the word type and enter is that when I say type you need not
strike the "Enter" key.
The screen should now look like this:
\input fvins.tex
Now after having copied your ACSII/text file onto the clipboard in
your local system, click on paste. Step
3 Type the "Esc" key and enter the following to save the
file: :wq ¬ Step 4
If your are unable to obtain permission to access the file from
your browser, enter the following at the prompt in the directory of
the file you are trying to access: $ chmod o+r
*.html ¬ where the star represents the file name.
ReferencesTOC
|