entr - Run arbitrary commands when files change
mcron - mcron is GNU's implementation of cron. It is a 100% compatible replacement for Vixie cron.
Anacron - Anacron is a periodic command scheduler. It executes commands at intervals specified in days.
fcron - Fcron is a scheduler designed for Unix/Linux systems, especially usefull when your system is not up all the day long.
Guard (CLI Tool) - Guard is a command line tool to easily handle events on file system modifications.
BSI Hotel Booking System - BSI Hotel Booking System is a real time online hotel booking.