Big Dummy's Guide To The Internet Part 30

of "subscribe" to [email protected] You can get supporting doc.u.mentation for the project via anonymous ftp at ftp.lm.com in the pub/interpedia directory.

Chapter 9: ADVANCED E-MAIL

9.1 THE FILE'S IN THE MAIL

E-mail by itself is a powerful tool, and by now you may be sending e-mail messages all over the place. You might even be on a mailing list or two. But there is a lot more to e-mail than just sending messages. If your host system does not have access to ftp, or it doesn't have access to every ftp site on the Net, you can have programs and files sent right to your mailbox. And using some simple techniques, you can use e-mail to send data files such as spreadsheets, or even whole programs, to friends and colleagues around the world.

A key to both is a set of programs known as encoders and decoders. For all its basic power, Net e-mail has a big problem: it can't handle graphics characters or the control codes found in even the simplest of computer programs. Encoders however, can translate these into forms usable in e-mail, while decoders turn them back into a form that you can actually use. If you are using a Unix-based host system, chances are it already has an encoder and decoder online that you can use. These programs will also let you use programs posted in several Usenet newsgroups, such as comp.binaries.ibm.pc.

If both you and the person with whom you want to exchange files use Unix host systems, you're in luck because virtually all Unix host systems have encoder/decoder programs online. For now, let's a.s.sume that's the case. First, upload the file you want to send to your friend to your host site (ask your system administrator how to upload a file to your name or "home" directory if you don't already know how).

Then type

uuencode file file > file.uu

and hit enter. "File" is the name of the file you want to prepare for mailing, and yes, you have to type the name twice! The > is a Unix command that tells the system to call the "encoded" file "file.uu"

(you could actually call it anything you want).

Now to get it into a mail message. The quick and dirty way is to type

mail friend

where "friend" is your friend's address. At the subject line, tell her the name of the enclosed file. When you get the blank line, type

~r file.uu

or whatever you called the file, and hit enter. (on some systems, the ~ may not work; if so, ask your system administrator what to use). This inserts the file into your mail message. Hit control-D, and your file is on its way!

On the other end, when your friend goes into her mailbox, she should transfer it to her home directory. Then she should type

uudecode file.name

and hit enter. This creates a new file in her name directory with whatever name you originally gave it. She can then download it to her own computer. Before she can actually use it, though, she'll have to open it up with a text processor and delete the mail header that has been "stamped" on it. If you use a mailer program that automatically appends a "signature," tell her about that so she can delete that as well.

9.2 RECEIVING FILES

If somebody sends you a file through the mail, you'll have to go through a couple of steps to get it into a form you can actually use. If you are using the simple mail program, go into mail and type

w # file.name

where # is the number of the message you want to transfer and file.name is what you want to call the resulting file. In pine, call up the message and hit your O key and then E. You'll then be asked for a file name. In elm, call up the message and hit your S key.

You'll get something that looks like this:

=file.request

Type a new file name and hit enter (if you hit enter without typing a file name, the message will be saved to another mail folder, not your home directory).

In all three cases, exit the mail program to return to your host system's command line. Because the file has been encoded for mail delivery, you now have to run a decoder. At the command line, type

uudecode file.name

where file.name is the file you created while in mail. Uudecode will create a new, uncompressed binary file. In some cases, you may have to run it through some other programs (for example, if it is in "tar" form), but generally it should now be ready for you to download to your own computer (on which you might then have to run a de-compressor program such as PKXZIP).

9.3 FILES TO NON-INTERNET SITES

What if your friend only connects with a non-Unix system, such as CompuServe or MCIMail? There are programs available for MS-DOS, Apple and Amiga computers that will encode and decode files. Of course, since you can't send one of these programs to your friend via e-mail (how would she un-encode it?), you'll have to mail (the old-fashioned way) or give her a diskette with the program on it first. Then, she can get the file by e-mail and go through the above process (only on her own computer) to get a usable file. Remember to give her an encoder program as well, if she wants to send you files in return.

For MS-DOS machines, you'll want to get uunecode.com and uudecode.com. Both can be found through anonymous ftp at wuarchive.wustl.edu in the /mirrors/msdos/starter directory. The MS- DOS version is as easy to use as the Unix one: Just type

uudecode filename.ext

and hit enter.

Mac users should get a program called uutool, which can be found in the info-mac/util directory on sumex-aim.stanford.edu.

Think twice before sending somebody a giant file. Although large sites connected directly to the Internet can probably handle mega-files, many smaller systems cannot. Some commercial systems, such as CompuServe and MCIMail, limit the size of mail messages their users can receive.

Fidonet doesn't even allow encoded messages. In general, a file size of 30,000 or so bytes is a safe upper limit for non-Internet systems.

9.4 GETTING FTP FILES VIA E-MAIL

To help people without ftp access, a number of ftp sites have set up mail servers (also known as archive servers) that allow you to get files via e-mail. You send a request to one of these machines and they send back the file you want. As with ftp, you'll be able to find everything from historical doc.u.ments to software (but please note that if you do have access to ftp, that method is always quicker and ties up fewer resources than using e-mail).

Some interesting or useful mail servers include: [email protected] Files of "frequently asked questions"

related to Usenet; state-by-state lists of U.S. representatives and Senators and their addresses and office phone numbers.

[email protected] Information about the Electronic Frontier Foundation; doc.u.ments about legal issues on the Net.

[email protected] Back copies of the Computer Underground Digest and every possible fact you could want to know about "The Simpsons."

[email protected] Programs for many types of personal computers; archives of past postings from many Usenet newsgroups.

[email protected] s.p.a.ce-related text and graphics (GIF-format) files.

[email protected] Detailed information about Internet.

Most mail servers work pretty much the same -- you send an e-mail message that tells them what file you want and how you want it sent to you. The most important command is "send," which tells the computer you want it to send you a particular file.

First, though, you'll need to know where the mail server stores that file, because you have to tell it which directory or sub- directory it's in. There are a couple of ways to do this. You can send an e-mail message to the archive-server that consists of one line:

index

The server will then send you a directory listing of its main, or root directory. You'll then have to send a second message to the archive server with one line:

index directory/subdirectory

where that is the directory or directory path for which you want a listing. An alternative is to send an e-mail message to our old friend archie, which should send you back the file's exact location on the archive-server (along with similar listings for all the other sites that may have the file, however) Once you have the file name and its directory path, compose a message to the archive server like this:

send directory/subdirectory/file

Send off the message and, anywhere from a few minutes to a couple of days later, you'll find a new message in your mailbox: a copy of the file you requested. The exact time it will take a file to get to you depends on a variety of factors, including how many requests are in line before yours (mail servers can only process so many requests at a time) and the state of the connections between the server and you.

Seems simple enough. It gets a little more complicated when you request a program rather than a doc.u.ment. Programs or other files that contain unusual characters or lines longer than 130 characters (graphics files, for example) require special processing by both the mail server to ensure they are transmitted via e-mail. Then you'll have to run them through at least one converter program to put them in a form you can actually use. To ensure that a program or other "non-mailable" file actually gets to you, include another line in your e-mail message to the server: