Automatically detect the OS

[mithodin]

Some shell utilities differ from os to os, e.g. Mac OS uses a different version of coreutils than most Linux distributions. This leads to some commands not working, e.g.
please give me the date 2023-01-30 UTC as a UNIX timestamp
results in
date -d "2023-01-30 UTC" +%s
which does not work on Mac OS. If I ask specifically for Mac OS, the result
date -j -u -f "%Y-%m-%d %Z" "2023-01-30 UTC" +%s
works.

It would therefore be very useful to automatically provide GPT with the operating system in use to make the results work out of the box.