MATH DEPT Computer News, Volume 19

Those damned attachments!

I explain here how to extract and decode e-mail attachments of various kinds.

The longer you have been using the same old mail handler to do e-mail, the more likely you are to suffer from e-mail attachments that you either can't extract, or if you can extract, you can't decode.

If you still use Berkeley mail (i.e., if you type "mail" at a UNIX prompt) to do e-mail, you should really try to learn something better and newer to use. The best and easiest system for most casual users is the e-mail program called pine. It handles attachments better than elm and much better than mail. See How to use pine for a quick and simple pine tutorial for the basics. For those who insist on continuing to use only Berkeley mail, I explain how to use the command metamail below to extract attachments.

Another good way to view attachments is via Netscape Mail. Network News Volume 23 explains how to move mail with attachments over to Netscape Mail where you can usually click on an attachment to view it. (The attachments appear at the bottom of the e-mail. You can also click on the "paper clip" icon to toggle the showing of the attachment viewing box at the bottom of the screen.)

How to use pine to handle e-mail attachments

I assume here that you know the basics about pine as described at How to use pine.

The best way to learn how to do these things is to e-mail yourself an attachment. I have a DVI file called exm.dvi in the Math530 subdirectory of my home directory. Here's what I do to e-mail it to myself as an attachment. First I start pine by typing

pine

in an xterm window. Next, I use the arrow keys to scroll to the

C   COMPOSE MESSAGE -  Compose and send a message

line and push RETURN (or just type the shorcut "c"). Next I fill in the To: line with my own login id at math and push RETURN or use the down arrow to move to the next line. I skip the Cc: line (unless I want to impress someone else that I know how to do attachments). Next I fill in the Attchmnt: line with the string

~/Math530/exm.dvi

NOTE: The tilde (~) in this line stands for my HOME directory.

It is good form to put something like exm.dvi in the Subject: line.

Next I use the down arrow to move into the Message Text area and jot myself a note. Finally, I type CONTROL-x to send the mail in pine and type "y" to confirm that, yes, I really do want to send it.

In a few seconds I receive my e-mail. I go back to the Folders List and get to my INBOX. I scroll down to highlight the message from myself with the attachment and push RETURN. After my little note to myself, I see

[Part 2, ""  Application/OCTET-STREAM (Name: "exm.dvi")  4.6KB]
[Cannot display this part. Press "V" then "S" to save in a file]

Next, I type "v" and make sure the attachment I want to save is highlighted. Then I press "s" to save the attachment in a file. I get prompted to save the file as exm.dvi in my HOME directory. If that's ok, I just type RETURN. If it's not ok, I backspace over the default filename and type something like

~/Math530/exm_copy2.dvi

and push RETURN. Then I type "e" for exit and "q" for quit and pat myself on the back.

metamail

If you don't want to use pine instead of plain old Berkeley mail or elm, you'll need to use a command like metamail to handle attachments. I'll give a couple examples of how to use it here. The first example handles an encoded text attachment.

Here is a typical attachment bummer that, if you haven't experienced yet, you will soon. Someone sends you an e-mail with an important text message included as an attachment. You might actually be able to read the text of the attachment in your mail program (like elm). Now you save the e-mail to a file because you want to use it somewhere else. But when you open the file to edit, you find something like this:

--16387385-3703-954786724=:97
Content-Type: TEXT/PLAIN; charset=US-ASCII

Dear Steve,
The attachment contains my important report.
Best,
Sam

--16387385-3703-954786724=:97
Content-Type: TEXT/PLAIN; charset=US-ASCII; name="bell.tex"
Content-Transfer-Encoding: BASE64
Content-ID: 
Content-Description:
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....etc.
....etc.
....etc.
DQogVGhlIGRlZmluaXRpb24gMi42IGlzIHVubmVjZXNzYXJ5IGFuZCBpdCB3
b3VsZCBzdWZmaWNlIChhbmQgaW4gbXkNCiB0aGlua2luZyBiZSBtb3JlIGNs
ZWFyKSBpZiB0aGV5IHdyb3RlICRccHNpXntudH0gPSBccHNpX3tudH0kDQog
YXMgdGhleSBkbyBsYXRlciBpbiB0aGUgcGFwZXIuDQogXHZza2lwIDAuNWlu
DQoNClxlbmR7ZG9jdW1lbnR9DQo=

The problem here is that the text file attachment has been encoded using BASE64 conventions. Elm decoded it for viewing, but not for saving. To decode and save the file, you can do this:

Save the e-mail to a file called tempmail (for example). Next, type

metamail tempmail > filename

where filename is the name of the file where you want to put a decoded copy of the e-mail. The lines of gibberish above should be converted to readable text in filename.

If the file tempmail above had been an encoded binary file, like a DVI or PDF file, then instead of sending the output of metamail to a file called filename, you should just type

metamail tempmail

and the .dvi or .pdf files would be created in the same directory where the file tempmail resides. (If you have a lot of files in your home directory, you might consider creating a temporary directory called, say Temp, and moving the file tempmail there before running this command. For example, if you do this:

mkdir Temp
mv tempmail Temp
cd Temp
metamail tempmail

you will find all the new files easily in the Temp directory.)

What metamail does with a jpeg attachment is to ask whether you want to view it with xv. If you answer "yes" and click on the resulting picture with the right mouse button, a menu will appear allowing you to rotate, crop, and save, etc.

If the file tempmail is an encoded MSWORD file, you can follow the same steps. Assume that you have saved an msword document in a file called letter.doc. You can view the file by typing

abiword letter.doc

I have found that the abiword program in

/opt/local/bin/abiword

does not always properly print what it shows on the screen. To print your msword document, you might need to ftp the file to a Windows machine. (Be sure to set the mode to BINARY by typing binary at the ftp prompt before making the transfer.) A similar story applies to files identified as mac-bin-hex. They need to be transfered to a mac and then uncompressed using stuff-it.

If your attachment originated from the web and is in the HTML language, see Network News Volume 23 for how to move it over to Netscape Mail for viewing.

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