Calculate MD5 checksum of a directory
Solution 1:
Sure - md5sum directory/*
If you need something a little more flexible (say, for directory recursion or hash comparison), try md5deep.
apt-get install md5deep
md5deep -r directory
To compare a directory structure, you can give it a list of hashes to compare against:
md5deep -r -s /directory1 > dir1hashes
md5deep -r -X dir1hashes /directory2
This will output all of the files in directory2 that do not match to directory1.
This will not show files that have been removed from directory1 or files that have been added to directory2.
Solution 2:
If you'd like to see what's different (if anything) between two directories, rsync would be a good fit.
rsync --archive --dry-run --checksum --verbose /source/directory/ /destination/directory
This will list any files that are different.