FTP Tutorial

What is FTP?
FTP for Unix
FTP for Windows
FTP for Macintosh
FTP Site Searching

This is a tutorial to provide basic FTP concepts and commands to allow the use of this simple yet powerful client/server application for the transfering of files.

What is FTP?

FTP is an acronym for File Transfer Protocol. FTP is a client/server application that allows the transfer of files between computers. This transfer can take place between a mainframe and a local terminal, or as a transfer of information over the Internet between your computer and a distant server. FTP is a powerful application which allows users to access archives that are available on a large number of computer hosts. The key elements of FTP are:

finding FTP sites from your client based system
establishing a connection with the server
developing an ability to search through "archives" to retrieve information
using FTP commands to facilitate the transfer of information
allowing for the differences in file types and compressions techniques.

The idea of client/server is important here - that you, the "local" client, are initiating a communication pathway with a "remote" server that may contain public information of interest to you.

We will look at some of the basic commands and tools for FTP, and then point to other sources for a more detailed discussion of the subject matter.

We will begin our discussion of FTP with an explanation of some of the commands used in Unix FTP, in order to develop an understanding of what is happening underneath the screen interface. We will then discuss the more user-friendly GUI applications for Windows and Macintosh.

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FTP for UNIX

Basic Commands

Since UNIX is a command line environment, we should introduce some of the basic commands that are used to establish an FTP session and to instruct the server on what the client is requesting. Some of the most commonly used commands are:

open initiates the session between the client and the server
nlist, dir, ls list the heirarchical organization of files on the remote server
cd allows you to change directories on the remote computer either up or down
pwd gives the client a chance to view the current directory and pathway on the remote host
lls, lcd, lpwd are the ways in which you can do the above for managing your local files
get allows you to retrieve a file from the server down to your local client computer.
put allows you to place a file from your client up to the remote server computer.
mput/mget are the same as above but allow for multiple files to be manipulated with a single command
prompt sets interactive prompting; "on" is a safety feature prompting you for verification of each step of the multiple commands, "off" allows the commands to act unimpeded
ascii/binary allows to specify the type of file to be transferred
quit ends the connection and ends the session.

To find the full array of commands, type help or ? at the FTP> prompt. This will instruct ruby to show all the available commands for effective FTP use; the above list is by no means exhaustive but does give the most commonly used commands.

Initiating a Session

For the sake of example we will assume that you are attempting to establish an FTP session from your Ruby account (your account on the SILS server) to another remote server computer (sunsite.unc.edu, for example). Once you have logged into Ruby, you could then start an ftp session by simply typing ftp at the prompt. The prompt then changes to look like: ftp>. At this you can then type: open sunsite.unc.edu. If you have an account on sunsite (or whatever remote computer you are connecting to), you can login with your username and password. If you don't, some servers allow anonymous ftp sessions, which simply means that you use 'anonymous' as your userid and your email address as your password when logging in to the remote comuter. A typical login, with client commands emboldened, is shown:


~ % ftp
ftp>open sunsite.unc.edu
Connected to sunsite.unc.edu.
220-
220 calzone FTP server (Version wu-2.4(4) Mon Jan 13
16:10:34 EST 1997) ready.
Name (sunsite.unc.edu:stear):anonymous
331 Guest login ok, send your complete e-mail address
as password.
Password:
230 Guest login ok, access restrictions apply.
ftp>

Getting What You Want

Once in any FTP server, you can navigate through the lists of directories and files to find out what is available. This is done by using the (l)cd, (l)ls and others like them to direct the navigation and the downloading of the files. Since the organization of directories and files is structured heirarchically, it may be easy to lose the way when looking for a document. In order to allow clients to keep up with their paths of searching, the command pwd becomes useful, prints the current (or working) directory. Before a file is requested by the client to be downloaded from the server (get command) or that the client wishes to upload onto the server (put command), two conditions must be considered

Issues concerning file permissions
Whether the file being transported is in Binary or Ascii mode

Briefly, one should view the permissions in UNIX to know for whom it is readable, writeable, and executable. These permissions can be viewed by using either the nlist or dirinfo commands. The client must also be aware if the file being transported is a text file or any other kind of file. In general, the transfer mode should be set to ascii for text-only files, and to binary for all others (including .gif, .doc, and any executable files).

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FTP for Windows

The FTP application for Windows is call WS-FTP and is a GUI-based file-transfer client that allows for a much easier client/server interaction.

WS-FTP is initiated by double clicking on the icon for it in Windows 95. The session starts with a logon procedure, and then graphically represents the client and the server by two opposing tables of directories and files. By logging in you specify yourself as the local system, and allow ruby (or any other ftp server) to be the remote system. The directories can be changed easily enough, both on the remote computer and on the local client hard drive by simply clicking on the change directory button.

In order to FTP a file, one can simply look through the directories of the server to identify the file(s) of interest. You then make sure that the directory where you want to put that file in is open in your local system. You can click on either binary or ascii transfer mode, depending on what kind of file it is (you can also let the program decide by setting it to auto). Then, clicking the arrow in the direction you want the file to be transferred (client to server or vice-versa) moves the file into the other computer.

In terms of permissions, the WS-FTP program makes it very simple to set or re-set permissions. One need only to double-right click on the file of interest and choose the CHMOD command to set the permissions with the mouse.

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FTP for Macintosh

FTP applications for Macintosh are unique in their feel interface, but the underlying features of file transfers between clients and servers are very similiar to the WS-FTP mentioned above.

One Macintosh application is called Fetch and is associated with a little dog running across the screen to fetch information. It has the same basic setup as Windows 95 does. The only setback it has to the Windows system is that it is not clear in showing exactly where the file is coming from and where it is going from the server, it only shows the directories for the client.

One simply needs to click on this application and the helpful GUI interface leads you through the steps for file transfer.

Another useful FTP program is called Anarchie. The basic metaphor for Anarchie is based on Finder windows. Each window corresponds to a directory on a remote ftp server. You can have multiple windows open at once, so you can interact with different ftp servers, or different directories on those servers, at the same time. You can drag and drop files between the windows and the Finder, or just double click to transfer the file. You can even upload or download entire directories by dragging and dropping a directory from or to a window!

Anarchie also has two searching facilities to find files on the internet. "Archie" searching will let you search the one of the various archie servers around the internet, which attempt to catalog a lot of files available via ftp. Anarchie also includes the ability to search the entire Info-Mac archive database, which will tell you the location of any file in the comprehensive Info-Mac library. Info-Mac is the main repository of Macintosh shareware and freeware.

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