File Transfers

The World supports the four most widely used file transfer programs, the XMODEM, YMODEM, and ZMODEM family and KERMIT. This document provides a comprehensive overview of the basics involved with uploading and downloading files. For complete details on the Unix versions of these file transfer programs, please refer to the online manual pages. 

  For ZMODEM, YMODEM, AND XMODEM:	world% man sz


  For KERMIT:				world% man kermit
The term "local host" refers to the computer at your home or office. Whenever you see this word, you need to think of your computer rather than The World. The term "download" means to send a file FROM the World TO your computer, and "upload" is to send a file FROM your computer TO The World. All World commands will be prefixed with the string "world%" to indicate that you should issue the command at the World's UNIX prompt. Please see the documentation for your local host software for information about commands or menuitem selections that affect file transfer at your local level.

Computer files have two basic flavors, binary and text. A text file contains readable text: letters, numbers, and punctuation, usually using the ASCII character set. Unfortunately, there are three different common text file formats in use. The difference is in how the end of each line is marked, UNIX uses a Line Feed (Control-J), DOS and most personal computer operating systems use Carriage Return (Control-M) Line Feed pairs, some older systems like CPM and some Mac applications use just Carriage Return. As a result of these differences, the file transfer software must translate text file to the format used by the system receiving the file.

Binary files, on the other hand, contain arbitrary data and can be sent without translation. Of course a machine-specific binary file can only be used on a designated machine. However, a binary data file can be used with any computer that also has the same application. For example, two different people, one using Macintosh and one using MSDOS, can indeed exchange spreadsheets if both people are using the same spreadsheet application.

When performing file transfers, special care must be taken to ensure that text files are transferred as text files and binary files are transferred as binary files. Examples of both binary and text file transfers are provided.

Selecting a protocol

The most important factor when choosing a file transfer protocol is speed. You want to use the fastest protocol your software supports. In order from best to worst: ZMODEM, Sliding Windows KERMIT, YMODEM-g, YMODEM-1K, YMODEM, XMODEM-1K, XMODEM/CRC, XMODEM, Kermit.

You may not see all of these options listed: your software may automatically use YMODEM-1K when you select "YMODEM", and most default to XMODEM/CRC, when XMODEM is selected, so check your software's manual to determine which protocols are supported. Sliding Windows KERMIT is a fairly new extension to KERMIT and is not supported by most software. Note that YMODEM-g should only be used with error correcting (MNP or V.42) modems and hardware flow control.

The chart below describes how to select the different protocols when starting the transfer on The World: 

Protocol		Download	Upload
------------------------------------------------------
ZMODEM			sz		rz
Sliding Windows KERMIT	kermit -v 3     kermit -v 3 -e 1000
YMODEM			sb		rb
YMODEM-g(1)		sb
YMODEM-1K(2)		sb -k	  	rb
XMODEM-1K(2)		sx -k		rx -c
XMODEM/CRC(3)		sx		rx -c
XMODEM			sx		rx
Kermit			kermit		kermit




(1) YMODEM-g can only be used when downloading files.  If your side
    requests YMODEM-g sb will automatically enter that mode.
(2) The sender must request XMODEM-1K or XMODEM-1K.  You can use
    XMODEM-1K without CRCs (that is no '-c' with rz) but this may cause
    transmission errors to go undetected.
(3) The receiver must request XMODEM/CRC.


Use this chart with the examples that follow.  For instance, if you
wanted to use YMODEM-1K replace "sb" in the example with "sb -k".

Using ZMODEM, YMODEM, or XMODEM

This section describes how to use the XMODEM protocol family for file transfer. Check the documentation on your local host software for details on how to use it from your end. Most software will automatically recognize the beginning of a ZMODEM download when you enter The World transfer command. YMODEM and XMODEM will usually have to be started by hand.

The most common type of file transfer is moving a text file. The various local host computers, Macintosh, IBM DOS, Amiga, etc. use different characters to indicate the line breaks. To guarantee compatibility, use the option "-a" to indicate a text file transfer.

To abort a Zmodem file transfer, use the Control-x character. You may need to type several Control-x characters before the transfer aborts.

Transferring a text file with ZMODEM

Again, please check the documentation for your local host software for details on how to handle file transfers from your end, as we only describe those commands issued from your World account, below.

To receive a text file at World from your local host (upload) use:

world% rz -a

To send a text file from World to your local host (download) use:

world% sz -a filename

The filename you specify will be downloaded to your local host.

To receive a binary file at World from your local host (upload) use:

world% rz

To send a binary file from World to your local host (download) use:

world% sz filename

Transferring a text file with XMODEM

To receive a text file at World from your local host (upload) use:

world% rx -a filename

A new file with the name specified will be created on The World.

To send a text file from World to your local host (download) use:

world% sx -a filename

The filename you specify will be downloaded to your local host.

To receive a binary file at World from your local host (upload) use:

world% rx filename

To send a binary file from World to your local host (download) use:

world% sx filename

Transferring a text file with YMODEM

To receive a text file at World from your local host (upload) use:

world% rb -a

To send a text file from World to your local host (download) use:

world% sb -a filename

To receive a binary file at World from your local host (upload) use:

world% rb

To send a binary file from World to your local host (download) use:

world% sb filename

Using KERMIT for file transfer.

Kermit offers either an interactive mode or a command level mode. To enter the interactive mode, simply use: 

	world% kermit
	C-Kermit 5A(188), 23 Nov 92, SunOS 4.1 (BSD)
	Type ? or HELP for help
	C-Kermit>

Once in kermit, type ? for additional details.

To abort a kermit file transfer, use the Control-C character. You may need to type several Control-C characters before the transfer aborts.

The following examples are for the command level mode of kermit.

To receive a text file at World from your local host (upload) use:

world% kermit -r

To send a text file from World to your local host (download) use:

world% kermit -s filename

To receive a binary file at World from your local host (upload) use:

world% kermit -i -r

To send a binary file from World to your local host (download) use:

world% kermit -i -s filename 

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