This Java program creates an MD5 database of all files in a directory structure, and then allows you to easily recheck the contents of the directory and notify you if any files has changed.
It does not (currently) detect removed files. It only computes MD5 sum if the "last modified" timestamp of the file has changed since the last run, unless the -nomtime option is used.
md5i [-db ] [-v] [-nomtime] [[-updatedb] -scan ] [[-alwaysignore] -check]
-db FILE uses FILE to store file data (default: ~/.md5database)
-v verbose: outputs progress information
-nomtime ignore file timestamps
-scan DIR scans DIR and all sub-directories
-updatedb updates the database instead of creating a new
-check DIR checks all files in DIR and its sub-directories
-alwaysignore Don't prompt on modified files: only report and ignore