File: gnupg.info,  Node: Scdaemon SERIALNO,  Next: Scdaemon LEARN,  Up: Scdaemon Protocol

6.6.1 Return the serial number
------------------------------

This command should be used to check for the presence of a card.  It is
special in that it can be used to reset the card.  Most other commands
will return an error when a card change has been detected and the use of
this function is therefore required.

   Background: We want to keep the client clear of handling card changes
between operations; i.e.  the client can assume that all operations are
done on the same card unless he call this function.

       SERIALNO

   Return the serial number of the card using a status response like:

       S SERIALNO D27600000000000000000000

   The serial number is the hex encoded value identified by the '0x5A'
tag in the GDO file (FIX=0x2F02).