gpg --command-fd and gpg-agent

[Jeffrey Stedfast]

In Evolution, we have our own interface to gpg (ie. not gpgme).

When signing, our command-line will generally look something like this:

gpg --no-tty --status-fd=# --command-fd=# --sign --detach --armor -u
<key id> --output -

There are absolutely no problems with this *unless* the user has
configured his/her gpg options file with 'gpg-agent' or whatever the
appropriate line is.

if they do that, then they get 2 passphrase prompts - one from gpg-agent
and one from evolution.

what I'd like to know is what is the appropriate way for me to deal with
this? is there some sort of mesg I can watch for on the --status-fd? or
is there a way for me to override their gpg-agent setting and just make
it use my prompt instead?

I'd be totally cool with letting gpg-agent take care of the prompting
for evo, but I need to know how to handle this. I'd prefer to not need
to use some checkbox in the evo settings for this as that can lead to
confusion and other problems 

(I'm sure we can all imagine the following: "oops, I checked the box
that says that I want evo to use gpg-agent but I didn't actually
configure gpg to use it and/or I don't even have gpg-agent installed so
evo never prompts me for my passwd")

thanks for any advice,

Jeff