status of a tap device ...

[Marc G. Fournier]

Quick question ... is there a command I can run that will tell me if a 
tap device is open?  I know I can do 'ifconfig tap0' and see the 'Opened 
by' line, but I want to do this within a perl script, for instance, akin 
to how I can use the fstat function to get information about a file ...

Rather avoid re-creating the wheel, so to say, if its already been 
created ...

Thx