在shell脚本里使用mkfifo命令创建named pipes可以实现简单的事件驱动， 避免poll（轮询）带来的时延（not real-time）和资源消耗的问题。

mkfifo

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❯ man mkfifo | head -n 12
MKFIFO(1)                    General Commands Manual                   MKFIFO(1)

NAME
     mkfifo – make fifos

SYNOPSIS
     mkfifo [-m mode] fifo_name ...

DESCRIPTION
     mkfifo creates the fifos requested, in the order specified.  By default,
     the resulting fifos have mode 0666 (rw-rw-rw-), limited by the current
     umask(2).
~

consumer

消费者以blocked的状态监听事件的发生，然后handle:

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#!/bin/bash

pipe=/tmp/testpipe

trap "rm -f $pipe" EXIT

if [[ ! -p $pipe ]]; then
    mkfifo $pipe
fi

while true
do
    if read line <$pipe; then
        if [[ "$line" == 'quit' ]]; then
            break
        fi
        echo $line
    fi
done

echo "consumer exiting"

producer

生产者往pipe里写入内容，触发事件：

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#!/bin/bash

pipe=/tmp/testpipe

if [[ ! -p $pipe ]]; then
    echo "Reader not running"
    exit 1
fi

msg=${1-"Hello from $$"}

echo $msg >$pipe