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I am on a 2015 MacBook Pro and have just updated to OS 12.01 Monterey, and to zsh on terminal.

I am able to create a checksum for individual files using shasum -a 256 (then drag in a file).

However, I need to know how to create a checksum for a folder.

Then I need to know how to create a compare checksum script or command.

AdminBee
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TracyuFitz
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  • Including subfolders or files only? – Hauke Laging Nov 18 '21 at 20:06
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    Does this answer your question? [How do I get the MD5 sum of a directory's contents as one sum?](https://unix.stackexchange.com/questions/35832/how-do-i-get-the-md5-sum-of-a-directorys-contents-as-one-sum) – Greenonline Nov 18 '21 at 21:35

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Here's what I would start with, using "scratch" as the source and "zork" as the new copy (which could be on a different dist). Note that I'm using the -a flag to cp so that file timestamps are preserved during copy.

% (cd scratch ; tar cf - .) | shasum -a 256
a17cacd171d6cbc2f6da028c8167b0602a1146a337f602de71529999fe471e0f  -

% /bin/cp -a scratch zork

% (cd zork ; tar cf - .) | shasum -a 256
a17cacd171d6cbc2f6da028c8167b0602a1146a337f602de71529999fe471e0f  -

If you want to compare the two sums directly, you could use

if [[ $((cd scratch ; tar cf - .) | shasum -a 256) == $((cd zork ; tar cf - .) | shasum -a 256) ]]
then
  echo match
else
  echo no match
fi
smolin
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  • This is fragile; the archive generated by `tar` will depend on how the filesystem orders files in directory listings, on how accurately `cp` copies holes in sparse files, in the case of macOS probably even on how the filesystem normalizes Unicode... – u1686_grawity Nov 19 '21 at 20:10
  • Interesting points @user1666 would it help to use find instead? ``` find scratch/ -type f -exec shasum -a 256 {} + | cut -d' ' -f 1 | shasum -a 256 ``` – smolin Nov 20 '21 at 00:25
  • If you sorted the list of per-file shasums (though there's probably no need to throw away file names), then yes, otherwise it still depends on the "filesystem order". – u1686_grawity Nov 20 '21 at 10:39