#!/bin/bash

trap 'rm -f fifo' EXIT

mkfifo fifo || exit

: > fifo &
exec 3< fifo
read <&3 || echo EOF

# A writer opens, writes and closes after the reader has observed EOF but
# before the reader closes its end.
echo two > fifo && echo "wrote two"

# Closing the last open descriptor on the fifo discards the unread data. That
# goes for any process, including a reader exiting after EOF. Where it matters,
# keep a spare descriptor open.
exec 3<&-

echo three > fifo &
cat fifo