I use the command

find . -type f -exec sha256sum {} \; > sha256SumOutput

to hash every file in a folder hierarchy. Unfortunately, sha256sum doesn't get the file names from find in alphabetical oder. How can this be fixed?

I'd like to have them ordered before they are hashed so they are hashed in alphabetical order (this has a reason).

3

2 Answers

Using some pipes and sort

find . -type f -print0 | sort -z | xargs -r0 sha256sum > sha256SumOutput

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Explanation

From 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.

From man sort

 -z, --zero-terminated line delimiter is NUL, not newline

From man xargs

 -r If the standard input does not contain any nonblanks, do not run the command. Normally, the command is run once even if there is no input. This option is a GNU extension. -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. 

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Example

% 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

The values in the first column are the same, as the files doesn' have any content in my test.

4

You should be able to just pipe your output from find to sort.

9

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