File Transfer


File Transfers on SCN

You can upload and download files to and from your PC using a file transfer protocol that detects and corrects data transmission errors. SCN offers the Xmodem, Ymodem, Zmodem and Kermit file transfer protocols. See the "Work with Your Files" menu ("go files") when you log on. You can use these from within the Lynx browser, or from the Freeport menu.

When using a text-based user interface your mouse will not work with it since that device is designed for a graphical user interface (GUI). To select an item on a Freeport menu use your number keys. There are command line shortcuts you can use to jump to menu items, when logged in press the "?" (question mark) key to get a list of some of the commands or type "go" (without the quotes) to get the list of go commands <go command>.

The Lynx Web browser lets you download files directly to your PC. The Pine email program lets you save messages as files in your "work" directory.

If you're using Windows or a Macintosh or any other graphical system (GUI), you can also copy and paste short pieces of text directly into your editing window on SCN, when you're logged in and editing your files. However, long pieces of text may pause or lock-up.

Another way to transfer files to your SCN file space is to email them to your SCN email address as attachments.

To move files from your "work" directory to your "public_html" web-directory go to the Freeport "Work with files in your personal Web directory" menu ("go webfiles"). If you have an Information-Provider account be aware that your "personal" web directory is a different path than your "I-P" directory.


When to Use Zmodem

Use Zmodem to transfer files, whenever possible. If your communications program doesn't support Zmodem, or if Zmodem doesn't work well with your communications program, then try the older and simpler Xmodem protocol. You can use Zmodem or Xmodem if you dial up SCN directly.

While connected directly to SCN on a dialup line, you can upload and download any kind of files with Xmodem or Zmodem, including binary files. Binary files are files that contain non-text characters. Some examples are graphics, spreadsheet and word processor files.

All computer systems transfer printable characters unaffected. But when connected to SCN through an intermediate system (such as some public library dialup connections), the other system might block or change some control characters.

These control characters can also appear as data bytes in binary files, and filtering them can corrupt the file data. To overcome this problem, you can run a program that translates all the control characters in a file into printable characters. The recipient of the file can then use a similar program to change the file back into its original form.

One common type of encoding like this is a MIME type called Base 64. Most current email programs can decode it automatically. So can other programs that run on Windows and Macintosh computers, such as Wincode. If you must connect to SCN through a gateway that does not pass control characters unaffected, then before you upload a file to SCN to email it to someone with Pine, you can encode the file on your PC. Then you can upload it with Xmodem or Zmodem, and send it as an email attachment.

SCN has some programs archived that you can download from the Freeport & quot;go softutil" menu such a "Mpack" that can be used to manually MIME encode and decode files.


When to Use Text-Mode Kermit

While connected to SCN through most public library gateways, you'll have to use text-mode Kermit to download binary files such as .zip and .exe files at Internet file download sites. When using such connections, you'll also need to use text-mode Kermit to upload binary files.

An example of an Internet gateway that won't pass every control character unaffected is the King County Library System's connection to SCN through its dialup menu.

Text-mode Kermit automatically encodes each file as printable ASCII characters before transmission, and then automatically decodes the file at the other end before saving it in its original form. You can upload or download any file with Kermit, but Kermit transfers are often very slow.


More About File Transfer Protocols

SCN supports the Xmodem, Ymodem, Zmodem and Kermit protocols. Use one that your PC's communications program supports.


Using Your Communications Program with SCN

To use one of these file transfer protocols, first select the direction of the file transfer (to or from SCN) from the SCN file transfer menu ("go upload" or "go download"). Then choose a protocol from SCN the menu. Depending on which direction the files are going, SCN or your communications program will prompt you for file name.

In some cases you must escape back to your PC and issue your local Send or Receive command before the file transfer begins. On completion, return back to SCN and you'll see the file transfer menu again.

For example, a terminal-emulation program that came with some versions of Windows is called Hyperterminal. If you use Hyperterminal and want to upload a file to your SCN account, just "go" to the SCN "go upload" Freeport menu, then choose option "1", upload file, then on your Hyperterminal program open the "transfer" menu and select "send" then browse or type in the filename (wildcards might work for multiple files), and click "okay". To download from SCN with Hyperterminal you would use the SCN Freeport "go download" menu, choose option "1" (Zmodem), then type in the file name (if it's in your work directory, otherwise type in the full path), hit the enter-key and the file should download. Note that this is case-sensitive, you must use upper or lower case to match the filename.

It's normal to see a line of strange characters at the command prompt on your screen before and after a file transfer. Do not be alarmed. These accompany SCN's attempts to communicate with your PC via the file transfer protocol. Your communications program might be confused by these characters, especially on completion of a file transfer, causing it to display the SCN menu out of place on the screen. If you can't see the menu or the screen is garbled, type "r" to redraw the screen, or type "p" to return to the previous menu.


Binary (Default) and Text Mode Transfers

By default, all Xmodem, Ymodem and Zmodem file transfers are done in binary mode. This lets you transfer most files, including binary files like executable, graphics, spreadsheet and word processor files.

SCN text files have an ASCII Line Feed character at the end of each line. On MS-DOS and Windows systems, a new line is indicated by a Carriage Return character followed by a Line Feed. On a Macintosh, a new line is indicated by only a Carriage Return character. If you transfer a file created on SCN to your MS-DOS PC and type it to your screen, the lines will look like this:

     You might see
        something like
                 this.

     Instead of nice
     regular print that
     looks like this.

Some communications programs have a setting that automatically detects text file transfers and makes the necessary conversion. Others have a setting that replaces all incoming Line Feed characters with your PC's newline character combination, in text files.

If your communications program doesn't automatically detect the file type of a text file, then you can specify a text mode file transfer instead of using binary mode. This will cause the SCN file transfer protocol to replace every Line Feed character with a Carriage Return and Line Feed character combination, as it sends the file. To do this, precede the file names with "-t" like this:

    Please enter file(s) to transfer : jokes letter complaint

Will cause the files "jokes", "letter", and "complaint" to be transferred in binary mode without any newline conversion.

     Please enter file(s) to transfer : -t jokes letter complaint

Will cause the same files to be transferred with newline character conversion. This also works for Xmodem incoming file names. Most Kermits should be able to detect what kind of file is being transferred and do the conversion for you. Do not use the "-t" flag when transferring executable (.exe) or other binary files because if you do, they will not work.


Canceling a File Transfer

To cancel a file transfer, first cancel it at your (PC) end in your communications program. Then connect back to SCN and type several Control-X's until you see the prompt "Press RETURN to continue:" at the bottom of your screen, after this message.

("^X...") File transfer canceled at user's request.

Macintosh users don't have to issue a connect command to return to SCN.

If you haven't yet escaped back to your PC, and can see the SCN "Your Choice ==>" prompt on the screen, simply press Control-X several times to abort the file transfer.


Kermit Limitations

You must start a Kermit file transfer from SCN before you escape to your PC and give it a command to send or receive a file. This means that a Kermit "get" command will not work. Also, programs that allow you to send remote commands (such as change directory or fork/spawn a shell) will not work.


Kermit Example

To transfer a file from SCN to your PC using Kermit:

Select the menu option "Send a file from SCN to your PC."

Select "Kermit."

At the prompt, enter the name of the file you want to send.

You will see the message: "Escape back to your PC and give a RECEIVE KERMIT command..."

In your PC's communications program, then issue a Receive command.

Most Macintosh communications programs provide a menu option. For example, RedRyder users should go to the "File" menu and select "Receive File Kermit". At the completion of the file transfer, the program will automatically return you to SCN.

If you do not get a prompt, hit Return until you see the SCN file transfer menu.


File Storage Space

Each user has 5 megabytes of file space to use on SCN. You can temporarily use more than that, but please reduce your usage to under 5 megabytes as soon as you reasonably can. If possible, please transfer any extra files to your home PC or another system, and then delete them from SCN.

If your account is active and current (you've logged in to the SCN menus during the past 3 months), you have 2 Mb of inbox mail space. If your account is active but not current (you've logged in during the past 9 months but not the past 3 months), you have 1 Mb of inbox space. If you haven't logged in for more than 9 months, you have no inbox space and all your mail bounces back to the sender.

Your saved file folders (anything that isn't in your inbox) doesn't count toward the 1 Mb (or 2 Mb) inbox limit. Neither does your Web site. So even though the system reminds you when you log in that you are using more than 1 Mb of total file space, it's actually lumping all your files together when it reports that. The file space utility that's on the Work with Your Files menus calculates the space used in yet another way from that used by the login file usage report.


Sending Files as E-mail Attachments

With Pine, you can send files as email attachments. You can also receive files as email attachments, and save them in your work directory. The Base 64 MIME encoding that Pine uses when sending attachments increases the file size of an attachment by about one third. Many other email programs also use Base 64 to encode attachments. The largest email message that you can receive on SCN is 2 Mb, if your account is current and you have no other mail in your inbox. This means that the largest unencoded file size that someone can send you is 1.5 Mb.


FTP & SSH

Regular SCN accounts do not allow FTP access (except through a Lynx download). However, Information-Provider accounts and certain active volunteers have FTP access. If you are online using an ISP other than SCN and have FTP access on SCN, then using a traditional command-line FTP program which is common on most operating systems you would just type...

     FTP scn.org

...to start to login to SCN FTP. If you are using a graphical (GUI) FTP program the host name to connect to SCN is...

     scn.org

Some people prefer to use SSH because FTP has some security issues such as transmitting your password as plain-text over the Internet. Refer to www.openssh.org for details. The OpenSSH website has listings of various programs available for various operating systems. One alternative to using FTP for Windows users is to use PSFTP which can be downloaded from the PuTTY website.


Illegal Activities

SCN doesn't condone the use of its system for illegal activities. Using SCN to 'pirate' passwords, credit card numbers or other such data is prohibited. Any user found using the system to engage in the illegal distribution of such items will be removed from the system.


More Help

For more information, read the manual for your communications program. If you still can't solve the problem, ask a knowledgeable friend, or ask another SCN user who has a similar system. Or you can email the Help Desk help@scn.org

Updated April 6th, 2004 - help@scn.org