ev_bell can call external programs when the Linux kernel generates a simple sound event like the bell signal from the console. It looks for sound events on /dev/input/event*, parses them, and calls the external program afterwards. The fields of the event packet can be put inside of the argument string of that program.
XCOM is a system designed to support component based programming in Linux. It features a specialized IDL compiler that generates C++ code, in-process components, embedded metadata, most of the common numeric data types, narrow and wide string types, array, sequence, and struct types, and error reporting via exceptions.
Hawserwar's player objective is to "pull" the knot on the rope towards the player's end of the rope. The knot moves one step towards player every time player presses the right letter the game is showing for the player to type next. The knot moves one step away from player every time the player presses a wrong letter. These same rules apply for both players. The game uses FIFOs for communication so both players must be logged in to the same machine to play the game.