The ___________ command allows you to view or change serial port configuration.

Answer: setserial

Explanation:
setserial command helps to set or get the Linux Serial Port Information, setserial is a program designed to set and/or report the configuration information associated with a serial port.
This information includes what I/O port and IRQ a particular serial port is using, and whether or not the break key should be interpreted as the Secure Attention Key, and so on.