Interactive Internet Training Workshop Web Archives

MAP15: FTPMAIL

Posted by: Patrick Douglas Crispen
Date Mailed: Wednesday, November 2nd 1994 02:30 PM

Deja vu! :)


MAP15: FTPMAIL


     "The whole of science is nothing more than a refinement of
      everyday thinking." -- Albert Einstein, Out of My Later Years


Before we get to ftpmail, there are a few other things that I
want to discuss.

Yesterday I showed you how to retrieve a text file using FTP.
But how can a text file written on an IBM be read on an Apple
Macintosh or on a Unix workstation? Its easy -- thanks to something
called ASCII.

ASCII is the American Standard Code for Information Interchange,
and it is the standard format for transmitting textual data.
*Any* computer can read an ASCII text file. Without going too
in-depth into how ASCII works, let's just say that ASCII ensures
that the text in an ASCII text file will appear the same on any
computer regardless of the computer's brand name or operating
system.

ASCII is fine and dandy for saving and transferring text files,
but it won't work with non-text, data files -- like computer
programs. Data files must be saved in "Binary" (which is just
a bunch of zeros and ones).

Binary files are files that can only run on certain machines
or programs. Good examples of Binary files include shareware
software, Microsoft Word files, Microsoft Powerpoint presentations,
satellite weather images, and sound files.

Remember, ASCII files are just 'plain' text files that can be
read on any computer, and Binary files are files that can only
be run on certain computers or programs.


Unfortunately, there is no universal default transfer mode
for FTP clients. Some clients use ASCII as the default, and
others use binary. This means that unless you tell your FTP
client to do otherwise, all of your files will be transferred
in the default transfer mode.

If your client's default transfer mode is ASCII and you try to
retrieve a Binary file without first resetting the transfer mode,
your Binary file will be transferred in ASCII and the file *WILL
NOT WORK* once you get it.

Fortunately, changing the transfer mode in FTP is easy. All that
most of you have to do to change the FTP transfer mode from ASCII
to Binary is type

          binary

right before you get the file, and the file will be transferred to
you in Binary format.

To change back to ASCII transfer mode, just type

          ascii

and FTP will reset its transfer mode to ASCII.

If you ever forget what transfer mode you are currently using --
something that I do *ALL* of the time -- all you need to do is
type

          status

and your computer will display a whole bunch of information,
including your transfer mode :)

BTW, how can you tell if a file is an ASCII file or a Binary
file? Well, take a look at the extensions (remember, an extension
is the stuff at the end of the file name -- the extension for
CRISPEN.DOC is .DOC; the extension for SQUIRREL.TXT is .TXT).
If the file's extension is .doc or .txt, or if the file does
not have an extension, it is a good bet that the file is an
ASCII text file. If the file has a weird extension -- like .gif
or .zip -- it is a good bet that the file is a Binary file.
There are, of course, always exceptions to this rule.

The "duck theory" also works pretty well in determining if a
file is an ASCII or Binary file. The duck theory says that if
it looks like a duck, waddles like a duck, swims like a duck,
quacks like a duck, and is seen hanging around with other
ducks ... it is probably a duck.

Using the duck theory to determine if a file is an ASCII or
Binary file, you can safely assume that if you have a file that
looks like a ASCII text file and is seen in the same directory
as other ASCII text files, you can safely assume that the file
that you are looking at is, in reality, a DUCK :)

(First squirrels ... now ducks ... this workshop is getting to me)


MULTIPLE FILE TRANSFERS:


How can you transfer multiple files at the same time? Simple! Use
the "mget" (multiple get) command!

Let's say that I want to get every file in a particular directory
with the word "duck" in it. I would type

          mget duck*

The * (a.k.a. "splat") is a "wild card" that tells the client to
get every file that begins with the word "duck" and that has
any additional characters after the word "duck".

The best way to explain wildcards is to give you an example. Let's
pretend that I have a directory with the following files in it:

     duckreport.doc          ducket.exe
     duck1.txt               duck2.txt
     ducksoup                duck.gif

Where I place the wildcard in my mget command will determine
what files I get:

     mget command:         files it would retrieve:

     mget duck*            duckreport.doc; ducket.exe; duck1.txt;
                           duck2.txt; ducksoup; duck.gif
     mget duck*.txt        duck1.txt; duck2.txt
     mget duck.*           duck.gif

Before you continue on, take a minute and try to figure out why
each of the mget commands retrieved different files. If you can
figure it out -- and believe me folks, this is EASY -- you will
be a master of the mget command :)


FTPMAIL:


If your local Internet service provider does not have an FTP
client, you can still get FTP files by using a tool called
ftpmail!

The steps in a basic ftpmail session are pretty easy:

     1. Write an e-mail letter to an ftpmail site near
        you, and put the necessary ftpmail commands
        in the BODY of your letter.
     2. The ftpmail site will write you back and tell you that
        it has received your request, and will tell you the
        number of requests ahead of yours (I still think that
        the number that they give you is just a random, large
        number (but I am probably mistaken)).
     3. A day or two later -- yes, I said "day" -- the ftpmail
        system will e-mail you the file that you requested.
        The ftpmail system will also send you a copy of the
        "transaction" as it occurred between ftpmail and the
        remote FTP site (this transaction will look a lot
        like the examples in yesterday's lesson).

Today, I am going to show you how to get ASCII text files using
ftpmail. We'll talk about Binary files tomorrow.

The first step is finding an ftpmail site near you. ftpmail
was developed at the Digital Western Research Laboratory, and
their ftpmail address -- ftpmail@decwrl.dec.com -- is the most
widely known (and widely used) ftpmail address in the world.
Unfortunately, because of the traffic that this site sees, the
decwrl address is also sometimes the slowest ftpmail site in
the world :(   <--- a frowning smiley

There are other ftpmail servers around the world that may be
closer to you, and that may actually be faster that the decwrl
address:

          Australia      ftpmail@cs.uow.edu.au
          France         ftpmail@grasp.insa-lyon.fr
          Germany        ftpmail@ftp.uni-stuttgart.de
          Great Britain  ftpmail@doc.ic.ac.uk
          Ireland        ftpmail@ieunet.ie
          Sweden         ftpmail@lth.se
          USA            ftpmail@sunsite.unc.edu
          USA            ftpmail@ftp.uu.net
          USA            ftpmail@decwrl.dec.com

Once you have found a site closest to you, you are ready to start
sending commands to the ftpmail address! The commands, just like
all of the LISTSERV commands that I drilled into your head earlier
in the workshop, need to be in the BODY of your e-mail letter.

The body of you letter to the ftpmail site will actually have SEVERAL
commands in it. The basic FTPmail commands are, in order:

       reply <your Internet address>
          This tells ftpmail where to send the file(s) to.

       connect <ftp site address>
          This tells ftpmail the site that you want it to
          connect to.

       <transfer mode>
          This tells ftpmail if you want the files in ASCII or
          binary

       chdir <directory>
          This tells ftpmail in which directory the file that we want
          is located.

       get <filename>
          This tells ftpmail to get a specific file.

       quit
          Ends the ftpmail session

Yesterday, we ftp'd to ftp.sura.net, got into the /pub/articles
directory, and got the file fall91.issue

To do this using ftpmail, I need to send an e-mail a letter to
ftpmail@sunsite.unc.edu (or to any other ftpmail site), and the
body of my letter would look like this:

          reply pcrispe1@ua1vm.ua.edu
          connect ftp.sura.net
          ascii
          chdir /pub/articles
          get fall91.issue
          quit

NOTE: IF YOU SEND THIS TO AN FTPMAIL SITE WITHOUT CHANGING THE
REPLY-TO ADDRESS, THE FTPMAIL SITE WILL SEND THE FILE TO *ME*,
NOT TO YOU. PLEASE CHANGE THE REPLY-TO ADDRESS :)

A day or two after I send this letter to the ftpmail address,
I should see the file sitting in my e-mail box. Notice that I
said "should." The traffic at the various ftpmail sites is
often incredible, and sometimes requests get lost. If this
happens to you, you should just send your request again :)

By the way, the "dir" command works just as well in ftpmail as
it does in regular FTP! All you have to do is add the command
"dir" after the "chdir" command:

          reply pcrispe1@ua1vm.ua.edu
          connect ftp.sura.net
          ascii
          chdir /pub/articles
          dir
          quit


TOMORROW:  - FTP File Compression/Decompression
           - Binary files via ftpmail
           - A few more ftpmail commands (ie. chunksize).

HOMEWORK:

     1. If you do not have FTP access through your local
        Internet service provider,

        a. find the address of the nearest ftpmail site
           from the list above
        b. send a letter to that ftpmail site with the word
           HELP in the body of your letter
        c. ask your local Internet service provider if
           they have any size limits on messages to and
           from the Internet.

     2. If you *do* have FTP access through your local Internet
        service provider, make sure that you

        a. know how to access your FTP client
        b. know the commands that your client allows
        c. review MAP13 and MAP14


   PATRICK DOUGLAS CRISPEN    THE VIEWS EXPRESSED IN THIS LETTER DO NOT
    PCRISPE1@UA1VM.UA.EDU      NECESSARILY REPRESENT THE VIEWS OF THE
  THE UNIVERSITY OF ALABAMA      UNIVERSITY OF ALABAMA - TUSCALOOSA

      ROADMAP: COPYRIGHT PATRICK CRISPEN 1994. ALL RIGHTS RESERVED.

   To unsubscribe from ANY Roadmap workshop, send an e-mail letter to
   LISTSERV@UA1VM.UA.EDU which says UNSUB * in the body of the letter
---
TeleSys-II Mail to News Gateway
For information about this gateway, email info@tnet.com
Dimenet Network Page Generation Copyright (c) 2004-2005 DIMENET and TNET Services, Inc.
Module: archive.php - Version: 2.50 - Build: August 11 2013 00:08:58 MST
Valid HTML 4.01!   Valid CSS!