Thanks for the good idea. The "cat somedir/* | md5" command comes close, but it skips all the subdirectories of the main directory. There doesn't seem to be an option to have cat act recursively.
how about
tar -cf test.tar someDir | md5
&& rm test.tar???
the blue part creates a "tarball" (Tape ARchive) of the directory "SomeDir" and all its files and subdirectories recursively, and the gray part is an optional part to delete the tar file after you've run an md5 checksum on it.
If disk space is an issue while creating the temporary tarball, modify the command to read
tar -czf test.tgz someDir | md5
&& rm test.tgz instead. This will create a compressed tarball to run the checksum against, and, as before, optionally delete the zipped tarball after the md5 has been run on it. This second way takes a bit longer to execute, though, but disk space savings during the lifetime of the tarball can be quite significant. You won't gain anything, disk space savings-wise, with ".mov" files or ".gpg" files but you sure will with text-type files, like .doc, or .txt or .rtf.
So, out of the three methods, it appears to me that Etresoft's "find" method gives you an MD5 checksum for each and every file nested in the directory of interest. Not sure if that's what you were looking for or not. My (j.v.) "nozip" tar method took 53 secs to spit out a single md5 checksum value for a 210,032,640-byte directory (my ~/Library) on a iBook G4/800, but it required a temporary allocation of free disk space the size of what I tarring/md5ing. Cole's method on that same directory (find ~/Library -type f -exec cat {} \; | md5), didn't require allocating any temporary disk space, and took 96 secs to spit out a single checksum value. I didn't time Etresoft's or my "tar&zip" methods. So there you have it -- three methods to do the same thing, each with their own advantages and disadvantages. Utilize as appropriate to your situation.
I like your tar method. I think you are just so used to dealing with tarballs that you forgot an important plot point. You don't need the "f" option. You can just do "tar c
