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.

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.

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