UNIX for Advanced & Expert Users

I am using the following command to email a tex file as an attachment-

cat mailtext.txt | elm -s "Subject" emailAddr
where content of mailtext.txt is -
"Body of email"
[include foo.txt text/plain base64]

This will attach foo.txt with the email.

My problem is that the file foo.txt is ceated dynamically everytime with a timestamp. e.g. foo_<timestamp>.txt

So if this filename is collected in a variable-
sFileName = foo_<timestamp>.txt

How do I include this filename dynamically in the mailtext.txt file?

Any help would be appreciated.

Thanks.

Use a HERE document and interpolate the value of a variable containing the file name.

Code:

elm -s "Subject" emailAddr <<HERE
"Body of email"
[include $sFileName text/plain base64]
HERE

With this solution, you don't need the external file at all. (Of course, if you still need an external file for other reasons, you can create it from a HERE document and then simply keep the sending part like you already had it, perhaps modulo the Useless Use of Cat.)

Thanks for the solution ...

I am providing this command in a C program.

sprintf( cmd, "elm -s SUBJECT %s <<HERE \n %s \n [include %s text/plain base64] \n HERE ", emailAddr, sMailBody, sFileName );

This is sending the [include %s text/plain base64] part also in the email body along with the actual body text. And there is no file attached in the email.

Could you please help me with this ???

The <<HERE is a feature of the shell; you need to spawn a shell to get it working.

Code:

sprintf (cmd, "sh -c 'elm -s SUBJECT %s <<HERE\n"
  "%s\n[include %s text/plain base64]\nHERE\n'"l, emailAddr, sMailBody, sFileName);

You are not allowed any leading whitespace on the line containing the terminating HERE (at least not in many shells).

Couldn't you just open a pipe to "elm -s SUBJECT %s" with popen() and pipe in the content yourself, though? That's pretty much equivalent to using a HERE document. (And you avoild the pesky security considerations you always bump into when spawning a shell with user-supplied input.)

If the file truly is text/plain, what's the benefit of encoding it in base64, by the way?

Could you please explain me how to use popen() ?

It could be a pretty simple thing, but I m a novice in unix. It would be good if you could show me the command.

Googling for "popen examples" gets me e.g. popen