Windows 10 can read my .bin files but Ubuntu cannot?

I'm running a basic analysis script that requires two .bin files to be read in. On win10 the following works

d1=[];
d2=[];
filenameA= 'Results...A.bin';
filenameB='Results...B.bin';
fid1=fopen(filenameA,'r+');
fid2=fopen(filenameB,'r+');
chunk_size=1e6;
precision='uint64';
d1=fread(fid1,chunk_size,precision);
d2=fread(fid2,chunk_size,precision);

fclose('all');

and reads in the data perfectly fine. On Ubuntu this does not work. d1 and d2 end up just being 0 by 0 arrays. The error doesn't occur until later in the code (when I try to use a size of d1, d2) so I know that it isn't an issue about incorrect filename, working dir, or similar, because the code gets further than this bit. Why would this be an issue? Is it related to file line endings? can this be implemented as an argument with fread?

edit: MATLAB 2019b

[Walter Roberson]

as an experiment try adding an fseek to beginning of file. Or use 'r' instead of 'r+'

[Rik]

You shouldn't use flcose('all') if you have all file handles. Was the opening correct? I.e., what are the values of fid1 and fid2?

[Bruno Luong]

May be check the permission and ownership of the files

[Walter Roberson]

If there were a permission or ownership problem then the fopen() would fail.

[Bruno Luong]

To be correct FOPEN will returns negative fid then FREAD would fail.

As it also would fail with 'r+' flag (vs 'r').

[Rachel Clark]

Walter Roberson adding the lines

fseek(fid1,0,'bof')

did not work.

Rik, removing fclose does not fix the problem. No it appears the opening was not correct, fid1 and fid2 are just 1x1 arrays containing integers 3 and 4 respectively.

Bruno Luong, permissions for both files are set to read and write for group. Changing flag to 'r' does not work.

Thanks everyone for your suggestions. I'll update if I find a solution.

[Bruno Luong]

Do you have a try/catch somewhere on stop stack when calling this function?

(If reading fail it will return [] initialized on top of your code.)

Are you sure the file is not corrupted on linux? What is the size?

[Walter Roberson]

Bruno, I am not clear why you indicate that it would fail with 'r+' flag? 'r+' is valid to indicate reading and writing. It does not create the file if it does not exist and it should initially position at beginning of file, but it permits switching to writing in the same file (provided that you fseek each time you switch between reading and writing)

https://www.mathworks.com/help/matlab/ref/fopen.html#btrnibn-1-permission

[Bruno Luong]

In linux here is what happen if a file opened with 'r+' but doesn't have write permission:

$ touch toto
$ chmod -w toto
$ ls -alrt toto
-r--r--r-- 1 Bruno 197121 0 Nov  5 19:01 toto

MATLAB

>> fid=fopen('toto','r+')

fid =

    -1