Bubblegum is a small daemon written in C which watches a files access, modification and inode change times and MD5 checksums. It supports logging to a file or syslogd, running a command with file information expansions, interval adjustment, resetting and reloading files via signals and more. Tested on FreeBSD, MacOS X, Solaris and Linux.
If you want MD5 checksum file checking, you need to have libmd installed. If you don’t have an already packaged version for your distribution, get the source from the libmd Homepage.