A Class on the Net for Librarians with Little or No Net Experience

LESSON 23: FTP, PART 2: FILE RETRIEVAL

"Knowledge is of two kinds. We know a subject ourselves, or we know where we can find information upon it."

-- Samuel Johnson, 1755


What's the first thing you see when you successfully connect to an FTP host site? Well, with a graphic FTP client, you will see the root directory displayed as soon as you successfully complete your connection; in a command-based system, you'll have to type the "dir" command at the waiting prompt in order to bring up the root menu.

In either case, the remote site will take you to the root menu and display for you a list of available directories and files. If you have a graphic browser, most likely, the menu will be displayed in a fairly friendly format, listing files/directories available, and the date and time each was last altered. If your FTP client returns something like the following, however, don't panic.


  dr-xr-xr-x    2 root     daemon       512   Mar   4  1994   bin

  dr-xr-xr-x    2 root     daemon       512   Aug  17  1993   dev

  dr-xr-xr-x    3 root     daemon       512   May  26  1994   etc

  dr-xrwxr-x   23 ftp      ftpmaint     512   Mar  17 20:55   pub

  drwx------    4 26002    gopherma    1024   Oct   4 15:34   tmp

Relax! It's really not as incomprehensible as it first appears. The right-most column lists the extension names of files or directories accessible at the root level (here we see "bin", "dev", "etc", "pub", and "tmp"). Always look for the "pub" directory because that where you will usually find the files available to anonymous ftp users.

The left-most column tells you if the item is a file or a directory. If the very first letter of each line is a "d" or an "l," it's a directory; otherwise it's a file. What you're looking at above are directories. To get to files, you'll have to go to the next level. Remember: most clients only allow you to transfer individual files, not directories to your local system; so, on command-based systems, you must first open the directory to get to the files stored in it. That means you'll have to move from the root directory to the "pub" directory, by entering the command:

cd pub

(NOTE: Most clients will allow you to transfer multiple files from a directory using the MGET command and wildcards; e.g., MGET *.txt would get all files with the '.txt' suffix from the current directory. Many graphic clients will allow you to select a complete directory for transfer by selecting it with the mouse.)

The remote system will change directories from the root to the "pub" directory, inform you when the job is done, and wait for the next command. If you're working from a command-based site, you will once again have to prompt the remote system to display the directories and files available at the "pub" level, by entering the command:

dir

Now, the display looks something like this:


    -rwxrwxr-x   1 root   gopherma     301 Feb   9 13:39 .cache

    drwxrwxr-x   2 1002   gopherma     512 Jan  31 16:41 .cap

    drwxrwsr-x   3 1002   gopherma     512 Aug   5  1994 about

    -rw-rw-r--   1 1002   gopherma    1917 Jan  31 16.40 release

    drwxrwxr-x   5 1002   gopherma    1024 Dec  23 08:18 results

Here, you see 3 directories and 2 files. Remember --


    Lines that begin like this:  drwxr-x-x   are directories

    Lines that begin like this:  -rw-rw-r-   are files

You don't have to understand the combination of letters and dashes that make up the rest of the directory/file headings. They are "flags" that tell the FTP site who can look at and manipulate the files. In fact, you may safely ignore the figures on each line until you come to the set of numbers immediately preceding the date. These figures tell you, in bytes, how large the file is. For a directory, the number will usually be very large; a directory listing of 400-500 bytes is quite small.

The information on size is followed by a date telling you when the file or directory was last altered. When you go from the root directory to, say, the "pub" directory, everything will look pretty much the same except that, on the far right-hand side, you'll now see the subdirectory or file name.

Names can be rather complicated (long and perhaps in mixed case) and if you're using a command-based FTP program, you'll need to be careful to type them EXACTLY as they are listed when you reference them! Otherwise, the FTP server will be unable to locate the appropriate directory path for you.

If you're using a command-based system and you haven't located the file you want at this level, you may have to travel through several directories and subdirectories. Picture the directory paths looking like this:

directory --> subdirectory --> subsubdirectory --> filename.ext

If you're using a graphic FTP program, you won't be typing in commands at all; you'll be selecting files/directories with your mouse and sending commands by selecting pull-down menu options or buttons.

THINGS YOU OUGHT TO KNOW ABOUT FTP FILES:

PRACTICE RETRIEVING A FILE:

Now it's time to "get" a file. Let's try to FTP a file together using the basic commands I have given you in the previous lesson and here. For this purpose, I have stashed three public access files on a server at USC that are available to you via anonymous FTP. Each is a BCK2SKOL topical collection of sites: one in the field of Health and Medicine, one in Business, and one in Education. We'll practice retrieving the Health and Medicine file together and then I'll let you go after the Business and Education files on your own.

Here's what you do:

 

    ftp to this site:          mel.csd.sc.edu

    login as:                  anonymous

    password:                  your email address

    change directory command:  cd pub/bck2skol

    list directory command:    dir

    check the transfer mode:   ascii

    transfer the file:         get FTP1.HLT

    say goodbye:               quit

NOTE: While it is not necessary to use the "dir" command when you are given specific instructions for fetching a file, doing so will help you understand the directory paths you are following in this exercise.


YOUR ASSIGNMENT:

FTP VIA EMAIL

To FTP via email, send a message to one of the following FTP mail sites:

Leave the subject line blank and, remembering that you are talking to a machine, stick to the following commands:

FTP VIA GOPHER

You can sample an FTP gopher gateway at the University of Minnesota gopher. This site provides a list of popular FTP archives, and also gives you a tool for connecting to any anonymous FTP server server worldwide. Gopher hostname: gopher://gopher.tc.umn.edu (go to "Internet file server (ftp) sites").

FTP VIA WWW

NOTE: Hot versions of the BUSINESS, HEALTH AND MEDICINE and EDUCATION collections referenced in this lesson are also available to you if you have access to the Web.


* "BCK2SKOL" is a free electronic library classroom created by Ellen Chamberlain, Head Librarian, University of South Carolina Beaufort, and Miriam Mitchell, Sr. Systems Analyst, USC Columbia. Additional support is provided by the Division of Libraries & Information Systems, University of South Carolina Columbia.


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Links checked 9 March 1998. See the BCK2SKOL homepage for course update details.
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URL: http://www.sc.edu/bck2skol/fall/lesson23.html