Cron和bash脚本显示不同的日志。

Question

我有一个简单的脚本来寻找一个配对的蓝牙耳机，如下所示，并安排它在cron中运行每分钟。它工作并连接到配对的蓝牙耳机，当它被打开时，如果蓝牙设备按预期关闭，它就会失败。为了调试cron调度程序，我在日志中捕获了脚本的日志。该日志只添加0标准输出，而不添加1 stderr。

脚本

#!/bin/bash

TIMESTAMP=`date "+%d-%m-%Y %H:%M:%S"`

#rfkill block bluetooth ---Use this to block bluetooth
bluetoothctl power on
if [ $? == 0 ]
then
    echo "$TIMESTAMP Bluetooth is started.Connectting to paired device"
    bluetoothctl connect 74:45:CE:97:90:72
    if [ $? == 1 ]
    then
        echo "$TIMESTAMP Failed to Connect Sony headset. Please check the headset availability"
        bluetoothctl power off
        echo "$TIMESTAMP Stopped the Bluetooth"
    else
        echo "$TIMESTAMP Connected to Sony Headset via Bluetooth"
    fi
fi

<#>Cron:

#To Connect Bluetooth automatically
* * * * * /home/xxxxx/Documents/Shell/scripts/bluetooth.sh >> /home/xxxxx/Documents/Shell/scripts/logs/bluetooth.log 2>&1

当我手动运行脚本时，它会根据连接捕获stderr和stdout。

Changing power on succeeded
23-01-2022 22:12:59 Bluetooth is started.Connectting to paired device
Attempting to connect to 74:45:CE:97:90:72
Failed to connect: org.bluez.Error.Failed
1
23-01-2022 22:12:59 Connected to Sony Headset via Bluetooth
HP-Pavilion:~/Documents/Shell/scripts$

但是，无论连接如何，日志/home/xxxxx/Documents/Shell/scripts/logs/bluetooth.log的输出总是低于成功连接的输出。

23-01-2022 22:10:01 Bluetooth is started.Connectting to paired device
Attempting to connect to 74:45:CE:97:90:72
0
23-01-2022 22:10:01 Connected to Sony Headset via Bluetooth
23-01-2022 22:11:01 Bluetooth is started.Connectting to paired device
Attempting to connect to 74:45:CE:97:90:72
0
23-01-2022 22:11:01 Connected to Sony Headset via Bluetooth
23-01-2022 22:12:01 Bluetooth is started.Connectting to paired device
Attempting to connect to 74:45:CE:97:90:72
0
23-01-2022 22:12:01 Connected to Sony Headset via Bluetooth
23-01-2022 22:13:01 Bluetooth is started.Connectting to paired device
Attempting to connect to 74:45:CE:97:90:72
0
23-01-2022 22:13:01 Connected to Sony Headset via Bluetooth
23-01-2022 22:14:01 Bluetooth is started.Connectting to paired device
Attempting to connect to 74:45:CE:97:90:72
0
23-01-2022 22:14:01 Connected to Sony Headset via Bluetooth

有人能帮我弄清楚为什么每当蓝牙没有连接时，cron的日志就没有错误吗？

Answer 1

首先，即使您的手动运行也没有给出预期的结果。该设备未能连接，最终的输出应该是“没有连接到索尼耳机”。

选项1:问题在于"echo $?“。删除这个语句，你就会没事的。

选项2:回显$？总是计算为0，因此如果总是返回false并执行else语句。

所以，就像这样潜入一个变量。

蓝宝石连接74:45:CE:97:90:72 x=$？回波$x