I downloaded from Yahoo few years of a daily stock time series.
Before storing them into a singular yearly files, i cleaned them from the "ghost data".
Maybe you knows, sometimes, Yahoo downloaded files shows data also when markets are closed (e.g. 2016-01-01 for italian markets).
After the cleaning I tried to join two files (years) with the "append" command (it does not matter by terminal, script or graphic interface).
I had no result (no appending) but i had a "success message" in a dialog box (while using the graphic interface) and no clear error message using terminal or script.
"append" seems not working with "cleaned" files (but of course in a different situation "append" works fine) .
So I suppose there is a kind of default data integrity control.
I havent studied yet the "join" command so may be this problem is solvable in others ways but I ask if i have chance to append my files and if I am not wrong I suggest, for the next releases
a) a better failure message for this case of the "append" command;
b) an option to "force" the appending of apparently non contiguous data;
c) a possibility of managing data to insert back the cleaned data. I tryed to insert a 2016-01-01 (ghost) value but i was unable to keep it at the top of the data.