A basic terminal stopwatch written in C, partially as practice and also because I wanted it. Written in basic c. You only need gcc to compile it and nothing special otherwise. For all I know this works only on Linux, you can try MacOS. Windows, I doubt.
I think that for logistical reasons, I will output the running live timer to stderr and the results to stdout.
$ termstop [-a -s -q -v] [-t us-sleep] [-f save-file] [-d delimiter]
See the man page for an explanation of the options.
Press to create a new split.
Press 'h' to stop the program.
$ sudo make install