I am getting inconsistent block sizes from du
output
$ du -b acinclude.m4 aclocal.m4
2019 acinclude.m4
40203 aclocal.m4
$ du acinclude.m4 aclocal.m4
4 acinclude.m4 # 2019 / 512
40 aclocal.m4 # 40203 / 1024
What is causing this?