At least two ways to load a file:
unix > rex test.rex
test.rex loaded
rex > x;
[3, 9, 1, 2, 8, 7, 5, 6, 4]

rex > y;
[barley, beans, oats, peas]

rex > z;
[[1, 2], [3, 4], [5, 6]]
Method 1: Include the file name on the UNIX command line:
here
You can re-run the command without retyping, e.g. unix > !r