Usando alguns pipes e sort
find . -type f -print0 | sort -z | xargs -r0 sha256sum > sha256SumOutput
Explicação
De man find
-print0
True; print the full file name on the standard output, followed
by a null character (instead of the newline character that -print
uses). This allows file names that contain newlines or other
types of white space to be correctly interpreted by programs
that process the find output. This option corresponds to the -0
option of xargs.
De man sort
-z, --zero-terminated
line delimiter is NUL, not newline
De man xargs
-0
Input items are terminated by a null character instead of by
whitespace, and the quotes and backslash are not special (every
character is taken literally). Disables the end of file string,
which is treated like any other argument. Useful when input
items might contain white space, quote marks, or backslashes.
The GNU find -print0 option produces input suitable for this mode.
Exemplo
% ls -laog
total 4288
drwxrwxr-x 2 4329472 Aug 17 08:20 .
drwx------ 57 20480 Aug 17 08:20 ..
-rw-rw-r-- 1 0 Aug 17 08:15 a
-rw-rw-r-- 1 0 Aug 17 08:15 a b
-rw-rw-r-- 1 0 Aug 17 08:15 b
-rw-rw-r-- 1 0 Aug 17 08:15 c
% find -type f -print0 | sort -z | xargs -r0 sha256sum
e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 ./a
e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 ./a b
e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 ./b
e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 ./c
Os valores da primeira coluna são os mesmos, pois os arquivos não têm conteúdo no meu teste.