Nice article. See also: https://www.pixelbeat.org/programming/stdio_buffering/

It's also worth mentioning a recent improvement we made (in coreutils 8.28) to the operation of the `tail | grep` example in the article. tail now notices if the pipe goes away, so one could wait for something to appear in a log, like:

    tail -f /log/file | grep -q match
    then_do_something