I'm about to write a program for a racecar, that creates a txt and continuously adds new lines to it. Unfortunately I can't close the file, because when the car shuts off the raspberry (which the program is running on) gets also shut down. So I have no chance of closing the txt.
Is this a problem?
Yes and no. Data is buffered at different places in the process of writing: the file object of python, the underlying C-functions, the operating system, the disk controller. Even closing the file, does not guarantee, that all these buffers are written physically. Only the first two levels are forced to write their buffers to the next level. The same can be done by flushing the filehandle without closing it.
As long as the power-off can occur anytime, you have to deal with the fact, that some data is lost or partially written.
Closing a file is important to give free limited resources of the operating system, but this is no concern in your setup.
What happens if I don't close a txt file