Write a bash shell named X that takes 2 arguments: F and PID.

The X calls a local function named pop_up, which clears the screen and prints the contents of F files, in ascending order, on stdout.

The X will shut down when it receives the SIGINT signal.

The X traps SIGINT to operate "clean-up" before shutting down, ensuring the F worker processes are shut down and deleting the F files.