在 mosquitto 中接收到某个消息时，Shell Script 无法离开 while 循环

如何解决在 mosquitto 中接收到某个消息时，Shell Script 无法离开 while 循环

因此，如果某个消息到达我的 RaspBerry pi，我正在尝试运行此脚本以退出 while 循环。可悲的是它不起作用。不知何故，如果消息到达，它无法识别 j 设置为 false。

  #!/bin/bash


# This script subscribes to a MQTT topic using mosquitto_sub.
# On each message received,you can execute whatever you want.


set -x
j=true


while [[ $j == true ]]  # Keep an loop to reconnect when connection lost/broker$

do
mosquitto_sub -t parsec.stop -C 1 | while read -r payload

do
        # Here is the callback to execute whenever you receive a message:
        if [[ "$payload" == "parsec.stop" ]] || [[ $j == false ]]; then
         echo "Rx MQTT: ${payload}"
        j=false
       fi
  done

 sleep 1  # Wait until reconnection
done # &  # discomment the & to run in background (but you should rather run$

echo "end"

这是我在执行脚本时在 Shell 中得到的内容

+ j=true
+ [[ true == true ]]
+ mosquitto_sub -t parsec.stop -C 1
+ read -r payload
+ [[ parsec.stop == \p\a\r\s\e\c\.\s\t\o\p ]]
+ echo 'Rx MQTT: parsec.stop'
Rx MQTT: parsec.stop
+ j=false
+ read -r payload
+ sleep 1
+ [[ true == true ]]
+ mosquitto_sub -t parsec.stop -C 1
+ read -r payload

如您所见，它确实在消息到达后立即声明 j = false。 但它并没有离开循环。由于仍然显示 [[ true == true]]