At least one reason /dev/fd0 won't work with .1D input files is that there is special code for reading from stdin -- normally, the way a 1D file is read is it is first scanned to see how many numbers there are in each row, then it is rewound and the input is started over to actually save the results into the output array.

Later, I wrote a new function that works specifically with stdin (which can't be rewound). This function has various limitations that the generic function doesn't -- for example, it doesn't support [...] and {...} column and row selectors, or the '5@3.2' shorthand notation for 5 copies of 3.2.

You CAN use 'stdin' (instead of /dev/fd0) as the filename to read from standard input -- this is the generic AFNI way of specifying a 1D file to be read from a pipe -- but you still can't use column selectors on it, as you need. That could be added, but not today as I have to prepare for a presentation I'm giving early next week, and I'm already beginning to panic panic panic!