How to select a specific subkey for signing?

[Mark Doll]

Since the "default-key" option just selects a whole key and not a specific 
subkey, I currently use a different secret keyring with just the desired 
subkey in it to "force" signing with that subkey. I wonder if there's a 
nicer solution to this problem.

Mark.


P.S.: Here my key as an example:

doll@borg:/.amd/home/doll >gpg --list-secret-keys 0xDF2D08D3
sec  1024D/DF2D08D3 2000-02-29 Mark Doll <m.doll@gmx.net>
uid                            Mark Doll <markdoll@gmx.net>
uid                            Mark Doll <doll@tm.uka.de>
ssb  2048g/5524278A 2000-02-29
ssb  1024D/39B20E88 2001-07-19
ssb  2048g/E5BCB023 2001-07-19
ssb  1024D/84BA6C81 2002-06-10
ssb  2048g/6E84ADA1 2002-06-10


GPG chooses 0x84BA6C81, which is alright for normal mail signing. But
for signing other keys with (sub)key 0xDF2D08D3, I use this mutilated 
version:


doll@borg:/.amd/home/doll >gpg --no-default-keyring --secret-keyring 
keysignring.gpg --list-secret-keys 0xDF2D08D3
gpg: no secret subkey for public subkey 5524278A - ignoring
gpg: no secret subkey for public subkey 39B20E88 - ignoring
gpg: no secret subkey for public subkey E5BCB023 - ignoring
gpg: no secret subkey for public subkey 84BA6C81 - ignoring
gpg: no secret subkey for public subkey 6E84ADA1 - ignoring
sec  1024D/DF2D08D3 2000-02-29 Mark Doll <m.doll@gmx.net>
uid                            Mark Doll <markdoll@gmx.net>
uid                            Mark Doll <doll@tm.uka.de>