How to make shell output redirect (>) write while script is still running?

Question

I wrote a short script that never terminates. This script continuously generates output that I have to check on every now and then. I'm running it on a lab computer through SSH, and redirecting the output to a file in my public_html folder on that machine.

python script.py > ~/public_html/results.txt

However, the results don't show up immediately when I refresh the address. The results show up when I terminate the program, but as I said, it doesn't halt by itself. Is that redirect (>) being lazy with with writing? Is there a way to continuously (or with an interval) update the results in the file?

Or is it the webserver that doesn't update the file while it is still being written?

Answer 1

You need to flush the output sys.stdout.flush() (or smth) if you want to see it immediately. See this

Answer 2

stdout is buffered, if not connected to terminal.

You can change this policy to line-buffering via stdbuf

stdbuf -oL python script.py > ~/public_html/results.txt

So you don't have to flush in your Python script and keep it IO efficient, if line-buffering is not required.