With no arguments, the channel command displays the current console channel number.
When passed an argument of 0 upward, this command switches the console
channel to that channel number. The mapping between channel numbers and
physical channels is platform specific but will typically be something like
channel 0 is the first serial port, channel 1 is the second, etc.
When passed an argument of -1, this command reverts RedBoot to responding
to whatever channel receives input first, as happens when RedBoot initially
starts execution.
Examples
Show the current channel.
RedBoot> channel
Current console channel id: 0
Change to an invalid channel.
RedBoot> channel 99
**Error: bad channel number '99'
Revert to the default channel setting (any console mode).
