如何立即在日志文件中获取stdout / stderr？

Question

To run some Python program I use the following bash script:

python3 /MyProg.py 0>/dev/null 1>>output_log_file 2>error_log_file

However I can get information after the prog is terminated only. When program is running there are not any data in these files.

Can I override this behavior to get log data immediately? My OS is Raspbian.

Answer 1

I suspect the program needs to flush stdout and stderr periodically, via

import sys
sys.stdout.flush()
sys.stderr.flush()

Answer 2

It seems there is because it uses full buffering instead of line buffering. Try to use unbuffer before your bash command and you should get the output on screen immediately.