BBB Reducing TTYO0 Console Output
/dev/ttyO0 (UART0) is present on J1. This connector is designed to mate with a FTDI TTL-232R-3V3 cable (DigiKey #768-1015-ND). The output from syslogd is routed here, and it can make the port next to impossible to use. The printk levels can be elevated so only messages of a certain severity or higher are displayed.
Edit /etc/sysctl.conf and change the 'kernel.printk' to the following to eliminate all but bad message from the console
kernel.printk = 3 4 1 3
This will not take effect until the next reboot. For an immediate change, do this:
sysctl kernel.printk="3 4 1 3"