You can make your script executable and pass in the "$(realpath script.py)" or wrap it in shell script file for extra arguments:

#/bin/sh
exec python3 script.py arg1 arg2
# exec ./script.py arg1 arg2 # I don't remember if you need `./` here.

and then pass this script file instead.

I think adding support for arguments would be nice, but you can live without it just fine as I showed you. Plus passing multiple arguments to a single flag is very hard. It becomes super messy when quotes and escaping comes into play. There are very few CLIs that do this (find -exec cmd arg1 arg2 \;).

I haven't tested any of that, but it all should work.

I can't do either. Windows doesn't support #/bin/sh, and I don't have enough familiarity with a C compiler to create a special executable to do what I want, which seems like overkill.

I have a workaround for now (wrote a script to check the file mod time of the .pdf file), but I do think there should be a way to pass in arguments.

Plus passing multiple arguments to a single flag is very hard. It becomes super messy when quotes and escaping comes into play.

Understood. I'm not looking to pass in arbitrary commands; I can handle the specialization with my script. But at least it should be possible to specify python myscript.py or java -jar blahblah.jar or whatever.

Windows doesn't support #/bin/sh

I don't like shindows, but I'm pretty sure you can do something similar with a .bat file or something. But I wouldn't be surprised if it just doesn't have any alternative at all.

--open only runs once, so it wouldn't really work anyway, if I'm understanding the requirement correctly. But I think watching the PDF file is a good solution, so I don't think this warrants a new argument.