Get your trial version of...
Let's start with two DEB-Installation-Packages:
Install it with a graphical tool, like "gdebi" or "qapt". Or simply use the command line:
sudo dpkg -i smonitor-2.0.deb
sudo dpkg -i ttimer-2.0.deb
If terminal and file are not in the same folder you have to add the path, of course -- e.g.:
sudo dpkg -i /home/"NAME"/Downloads/ttimer-2.0.deb
sudo dpkg -i /home/"NAME"/Downloads/smonitor-2.0.deb
-- upgrade 20210814 ------
Adding jar files for other Linux distributions (not using .deb), other OS (like Mac OSx, Windows ...), or simply as a purist variant.
java -jar SMonitor.jar
try: java -jar SMonitor.jar --help
java -jar ttimer.jar
try: java -jar ttimer.jar -v
hint: [F1] when the timer is up
==============================================================