UPS Daemon.
I created this program a long time ago, it was created using FreeBSD version 2.0 and using the GCC compiler, later improvements and adaptations were made to the code to continue compiling. In 2005 I decided to publish in the FreeBSD ports system.
It is a system that monitors the serial port of the UPS to know when the power is gone or came back, it was created using the C language and using ShellScript to run the shutdown or reboot command.
See more details in the links below: