Question

I have two folders which I want to open with the same application. To me, both folders seem identical, but to the application, they don’t.

First, I used this command to find any differences in the contents of the folders:

find folder/ -type f -name * -exec md5 {} + | awk '{print $1}' | sort | md5

This command yields the same result for both folders. But then, I tried this command:

tar c folder/ | md5

This command yields different output for both folders. The command also takes longer to complete for one folder than for the other.

I’m using Mac OS X Snow Leopard. What is going on here?

Answer 1

tar c includes the folder name in it’s compression, so unless the folders have the same exact name that will cause a mismatch.

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Also remember that tar will try to recover the permissions used on files compressed, that might also cause a mismatch if the folders don’t have the same exact permissions, as well as ownership.

To see if permissions/ownership is the same for the two folders use something as the below, piped to sort | md5 or whatever.

find foobar -exec stat -f "%p:%N:%u:%g" {} \;

The above will have the folder name "foobar" in the output, you should strip that out, you could use something like this:

find foobar -type f -exec stat -f "%N:%p:%u:%g" {} \; | sed 's/^foobar//'

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My recommendation

If you just want to see if the contents of files and their corresponding file name matches, use the diff utility instead of your own custom written version, as below:

diff -r folder1 folder2

Documentation of diff

• manpages(5) Mac OS X Developer Tools Manual Page – diff