Comment by avar

How does Plan 9 deal the equivalent of this append-only pattern potentially causing corruption on Unix if you have multiple writers and the writes are larger than PIPE_BUF (4k by default on Linux)?

Most users of this pattern (concurrent updates to log files) get away with it because their updates are smaller than 4k, but if you're trying to write something as big as an E-Mail with this pattern you can trivially get interleaved writes resulting in corruption.