Creating hash for folder

Question

Hi, i need to create hash for folder, that contains some files. I already done this task for each of files, but i searching the way to create one hash for all files in folder. Any ideas how to do that?

(of course i can create hash for each file and concatenate it to some big hash but it's not a way i like)

Thanks in advance.

Answer 1

Concatenate filenames and files content in one big string and hash that, or do the hashing in chunks for performance.

Sure you need to take few things into account:

• You need to sort files by name, so you don't get two different hashes in case files order changes.
• Using this method you only take the filenames and content into account. if the filename doesn't count you may sort by content first then hash, if more attributes (ctime/mtime/hidden/archived..) matters, include them in the to-be-hashed string.

Answer 2

If you already have hashes for all the files, just sort the hashes alphabetically, concatenate them and hash them again to create an uber hash.

Answer 3

Create tarball of files, hash the tarball.

> tar cf hashes *.abc
> md5sum hashes

Or hash the individual files and pipe output into hash command.

> md5sum *.abc | md5sum

Edit: both approaches above do not sort the files so may return different hash for each invocation, depending upon how the shell expands asterisks.