copy a file to/from a target device
usage: fx cp [-r] [--to-target|--to-host] SRC... DST Copies a file from the host to the target device, or vice versa. -r: recursively copy directories --to-target: copy file SRC from host to DST on the target --to-host: copy file SRC from target to DST on the host The default is to copy files to the target.