Section: RXVT-UNICODE (1)
bell-command - execute a command when the bell rings
Runs the command specified by the "URxvt.bell-command"
a bell event occurs. For example, the following pops up a notification
bubble with the text ``Beep, Beep'' using notify-send:
URxvt.bell-command: notify-send "Beep, Beep"