I'm trying to get the md5sums the contents of a directory, but md5sum doesn't seem to have a -r option. Since there are directories inside the directory in question, I have to do this recursively, but I can't find out how. Any ideas?

Try this... go to the base directory (i.e. if the files you want to sort are in /home/joe/files then cd to there) and then run:
Note that that's a backtick (below escape on a US keyboard) around the find command, which includes an asterisk in quotemarks.

This will only list the m5sums for this files and print the filename, it won't compare the sum to anything else, but if you have a list of correct sums then perhaps you can run diff or something? You could always redirect the output to a file or to less if it scrolls off screen. Anyway, perhaps this will be of some help.

Piece of cake!
Suppose the directory you wish to sum is /whateverpath/yourdir
md5sum /whateverpath/yourdir/* >> md5sums.txt

will sum every file in the directory and place the sum for each file in the output file md5sums.txt

Of course, you can vary this command. You could use *.iso to do only files ending in .iso, for instance. You could keep adding files to the dir and md5sum /whateverpath/yourdir/newfile >>md5sums.txt
would add the result to the end of the original list. You could use one > to completely rewirte md5sums.txt You could cd to the directory, first , too.
cd /whateverpath/yourdir
md5sum *August*.iso >>md5sums.txt

and you could verify that the files had not been fudged by doing
md5sum -c md5sums.txt
For the greatest certainty, keep md5sum executable and the md5sums.txt in a readonly file like a CD.

Recursion can be done one level at a time:
md5sum *>>md5sums.txt
md5sum */* >> md5sums.txt and so on or you can tar the files and md5sum the result.


Has this been overkill?

No, because you didn't read the question - he needs to do it RECURSIVELY. The command you specified will only work for the files in the current directory, it won't recurse subdirectories.

I'll try these. Thanks guys .