I have a serial device under /dev/ttyS0 and an application that is reading from the serial device (but not writing to it). I wanted to listen in to the data that is coming in on the serial device but I believe the cat /dev/ttyS0 won't work becuase it is already opened by the application.
I can find the file descriptor in /proc/pid##/fd to /dev/ttyS0. Is there a way to tap into the data coming in on the serial line? I have root access if needed. I don't have the ability to modify the application.