How should I detect if I've got a reader/smartcard combo?

Grant Olson kgo at
Tue Jan 18 06:29:10 CET 2011

I've got a working patch on my machine that lets me unplug my
reader/smartcard combo at will.  But it still needs some cleanup on a
few things before I can send it to the list.  There's one thing in
particular I'd appreciate some advice on.

Right now I detect when the device is removed by catching a change in
the slot status.  When the slot status equals zero it looks like this
means the card has been removed.  At that point I unload the reader.

This is working fine for me, but I imagine its less than ideal for a
stand-alone reader.  I imagine we want to keep scdaemon attached to the

If it was just a cryptostick issue, I could just check the vendor id.
But I believe OmniKey and SCM both have similar devices.  Can I query
through an existing scdaemon function to see if there's a reader
attached?  Or look to see if a particular device exists?  Or should I be
doing something else completely?  Are there approaches that will work
better with Windows boxes?  Etc...

I actually did order a reader and stand-alone card last week after
killing scdaemon one too many times, so I should be able to test both
configurations once those show up.

Any and all input is appreciated.


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