python 文件在 bash 脚本中抛出奇怪的错误，但可以自己完美运行

Question

您好，我在树莓派上构建了一个 GPS 解决方案。

python 代码运行良好，直到我将所有内容都打包到一个 bash 脚本中……然后奇怪的事情发生了……

所以我有： 1. publish.py（此文件将 GPS 数据发布到 MQTT 主题） 2. listener.py（这个文件监听MQTT主题，用于测试目的） 3.job.sh（bash脚本运行一些命令publish.py文件） 4. crontab（我做了一个crontab，每10分钟运行一次来​​运行job.sh脚本）

发布.py

from gps import *
import time
from sense_hat import SenseHat
import json
import paho.mqtt.client as mqtt
import nacl.secret
import nacl.utils
import device

#initiate the device object
device = device.Device()

sense = SenseHat()
sense.clear()


timestamp = 0
latitude = 0
longitude = 0

# The callback for when the client receives a CONNACK response from the server.
def on_connect(client, userdata, flags, rc):
    print("Connected with result code "+str(rc))

    # Subscribing in on_connect() means that if we lose the connection and
    # reconnect then subscriptions will be renewed.
    client.subscribe("topic")

# The callback for when a PUBLISH message is received from the server.
def on_message(client, userdata, msg):
    print(msg.topic+" "+str(msg.payload))

client = mqtt.Client()
client.on_connect = on_connect
client.on_message = on_message

client.connect("mqtt.eclipse.org", 1883, 60)

# put the symmetricKey into box
file = open("/home/pi/Project/symmetricKey", "rb")
symmetricKey = file.readline()
box = nacl.secret.SecretBox(symmetricKey)

def getPositionData(gps):
    nx = gpsd.next()
    if nx['class'] == 'TPV':
        global timestamp
        global latitude
        global longitude
        print("##############")
        timestamp = getattr(nx,'time', "Unknown")
        latitude = getattr(nx,'lat', "Unknown")
        longitude = getattr(nx,'lon', "Unknown")
        #print "##timestamp: ", timestamp, "##Your position: lon = ", str(longitude), ", lat = ", str(latitude)

    return timestamp, latitude, longitude

def getSenseHatData():
    pressure = sense.get_pressure()
    temp = sense.get_temperature()
    humidity = sense.get_humidity()
    #print "pressure: ", pressure, "temp: ", temp, "humidity: ", humidity

    return pressure, temp, humidity

def encrptyMessage(body):
    encrpted = box.encrypt(body)
    return encrpted

gpsd = gps(mode=WATCH_ENABLE|WATCH_NEWSTYLE)

def run():
    try:
        print ("Application started!")
        while True:
            gpsData = getPositionData(gpsd)
            senseHatData = getSenseHatData()
            dictionary = {
                "timestamp": gpsData[0],
                "latitude": gpsData[1],
                "longitude": gpsData[2],
                "pressure": senseHatData[0],
                "temp": senseHatData[1],
                "humidity": senseHatData[2]
            }
            body = json.dumps(dictionary)
            encrptedBody = encrptyMessage(body)

            print (dictionary)
            try:
                client.publish('topic', payload=encrptedBody)
            except:
                print("message is not successfully sent...")
            time.sleep(1.0)

    except (KeyboardInterrupt):
        running = False
        print ("Applications closed!")

    return body

run()

job.sh

#!/bin/bash

sudo systemctl start gpsd.socket & #this is to start GPS socket

sleep 5

python /home/pi/Project/publish.py & #this is to run my publish.py

sleep 10

sudo systemctl stop gpsd.socket & #this is to stop the socket service

crontab

*/10 * * * * bash /home/pi/job.sh

奇怪的是

当我直接运行publish.py时，一切正常......但是当我运行job.sh时，代码会抛出错误

Traceback (most recent call last):
  File "/home/pi/Project/publishTelemetry.py", line 123, in <module>
    run()
  File "/home/pi/Project/publishTelemetry.py", line 97, in run
    gpsData = getPositionData(gpsd)
  File "/home/pi/Project/publishTelemetry.py", line 45, in getPositionData
    nx = gpsd.next()
  File "/usr/lib/python2.7/dist-packages/gps/gps.py", line 287, in next
    return self.__next__()
  File "/usr/lib/python2.7/dist-packages/gps/gps.py", line 279, in __next__
    raise StopIteration

你知道如果 python 和 bash 有这种奇怪的行为吗？？？

感谢您的帮助！！！

Answer 1

它完全按照应有的方式运行。您启动 gps 服务，然后异步启动您的脚本，10 秒后您停止 gps 服务。执行此操作后，读取循环会引发 StopIteration 以指示您无法获取新更新（因为服务已停止）。

假设这是预期的行为，您可以简单地捕获此异常并停止作业。