Writing a commandline tool in #Fortran:
https://www.draketo.de/english/free-software/fortran
In case you want to broaden your #programming skills. Fortran seems to be making a comeback (currently 11 in the Tiobe index: https://www.tiobe.com/tiobe-index/fortran/ ).
This is from 2017, written at the end of my Physics PostDoc where I used quite a bit of Fortran and learned to appreciate it much more than I expected.