USAGE : cdx sample [options...] [files...]
| -h | --header=Mode | See cat |
| -s | --sample=Number | Number lines, fairly evenly spaced. |
| -r | --range=Ranges | e.g. 1-5,42,95-106 |
| -f | --for=By,From,To | for i=from; i<=to; i+= by |
Default behavior is --sample, with enough lines to fill the screen.