Bluetooth 使用rfcomm检查连接是否成功

我正试图用蓝牙加密狗将我的手机连接到我的RaspberryPi上（不想做任何惊天动地的事情，只想确定我的手机何时在该地区）。如果我打开手机的蓝牙并发出以下命令，我会得到以下输出（在有人开始向我鼓吹这是如何违反安全之前，让我提醒你，这不是我的实际手机蓝牙id）：

命令：

sudo rfcomm connect 0 AA:BB:CC:DD:EE:FF 10
echo $?

Connected /dev/rfcomm0 to AA:BB:CC:DD:EE:FF on channel 10
Press CTRL-C for hangup
0

sudo rfcomm connect 0 AA:BB:CC:DD:EE:FF 10
echo $?

Can't connect RFCOMM socket: Host is down
0

#!/bin/bash

phone1="AA:BB:CC:DD:EE:FF" #Address of phone
inside=1  # Whether the phone is 'inside' the house (0) or 'outside (1)

phoneDetected ()
{
   # Search for phone
   hcitool rssi $phone1 &>/dev/null
   ret=$?

   # If search was unsuccessful,
   if [ $ret -ne 0 ]
   then
      # Add phone
      sudo rfcomm connect 0 $phone1 10 &>/dev/null &

      # Note: the return code of rfcomm will almost always be 0,
      # so don't rely on it if you are looking for failed connections,
      # instead wait 5 seconds for rfcomm to connect, then check
      # connection again. Note this is not fool proof as an rfcomm
      # command taking longer than 5 seconds could break this program,
      # however, it generally only takes 2 seconds.
      sleep 5
      hcitool rssi $phone1 &>/dev/null
      ret=$?
   fi;

   # Case 1) we are now connected (ret=0) and we were previously outside (inside=1)
   if [ $ret -eq 0 ] && [ $inside -eq 1 ]
   then
      # change state to inside and do something (I am playing a song)
      inside=0
      mplayer /home/pi/documents/rasbpi/raspi1/media/audio/1.mp3 &>/dev/null
   # Case 2) we are no longer connected (ret=1) but we were previously inside (inside=0)
   elif [ $ret -eq 1 ] && [ $inside -eq 0 ]
   then
      # change state to outside and do something (I am playing another song)
      inside=1
      mplayer /home/pi/documents/rasbpi/raspi1/media/audio/2.mp3 &>/dev/null
   fi;
}

# run an infinite loop
while :
do
   phoneDetected $phone1
done

输出：

sudo rfcomm connect 0 AA:BB:CC:DD:EE:FF 10
echo $?

Connected /dev/rfcomm0 to AA:BB:CC:DD:EE:FF on channel 10
Press CTRL-C for hangup
0

sudo rfcomm connect 0 AA:BB:CC:DD:EE:FF 10
echo $?

Can't connect RFCOMM socket: Host is down
0

#!/bin/bash

phone1="AA:BB:CC:DD:EE:FF" #Address of phone
inside=1  # Whether the phone is 'inside' the house (0) or 'outside (1)

phoneDetected ()
{
   # Search for phone
   hcitool rssi $phone1 &>/dev/null
   ret=$?

   # If search was unsuccessful,
   if [ $ret -ne 0 ]
   then
      # Add phone
      sudo rfcomm connect 0 $phone1 10 &>/dev/null &

      # Note: the return code of rfcomm will almost always be 0,
      # so don't rely on it if you are looking for failed connections,
      # instead wait 5 seconds for rfcomm to connect, then check
      # connection again. Note this is not fool proof as an rfcomm
      # command taking longer than 5 seconds could break this program,
      # however, it generally only takes 2 seconds.
      sleep 5
      hcitool rssi $phone1 &>/dev/null
      ret=$?
   fi;

   # Case 1) we are now connected (ret=0) and we were previously outside (inside=1)
   if [ $ret -eq 0 ] && [ $inside -eq 1 ]
   then
      # change state to inside and do something (I am playing a song)
      inside=0
      mplayer /home/pi/documents/rasbpi/raspi1/media/audio/1.mp3 &>/dev/null
   # Case 2) we are no longer connected (ret=1) but we were previously inside (inside=0)
   elif [ $ret -eq 1 ] && [ $inside -eq 0 ]
   then
      # change state to outside and do something (I am playing another song)
      inside=1
      mplayer /home/pi/documents/rasbpi/raspi1/media/audio/2.mp3 &>/dev/null
   fi;
}

# run an infinite loop
while :
do
   phoneDetected $phone1
done

现在，如果我关闭手机的蓝牙并发出相同的命令，我会得到以下输出（同样，所有id都已更改以保护无辜者）

命令：

sudo rfcomm connect 0 AA:BB:CC:DD:EE:FF 10
echo $?

Connected /dev/rfcomm0 to AA:BB:CC:DD:EE:FF on channel 10
Press CTRL-C for hangup
0

sudo rfcomm connect 0 AA:BB:CC:DD:EE:FF 10
echo $?

Can't connect RFCOMM socket: Host is down
0

#!/bin/bash

phone1="AA:BB:CC:DD:EE:FF" #Address of phone
inside=1  # Whether the phone is 'inside' the house (0) or 'outside (1)

phoneDetected ()
{
   # Search for phone
   hcitool rssi $phone1 &>/dev/null
   ret=$?

   # If search was unsuccessful,
   if [ $ret -ne 0 ]
   then
      # Add phone
      sudo rfcomm connect 0 $phone1 10 &>/dev/null &

      # Note: the return code of rfcomm will almost always be 0,
      # so don't rely on it if you are looking for failed connections,
      # instead wait 5 seconds for rfcomm to connect, then check
      # connection again. Note this is not fool proof as an rfcomm
      # command taking longer than 5 seconds could break this program,
      # however, it generally only takes 2 seconds.
      sleep 5
      hcitool rssi $phone1 &>/dev/null
      ret=$?
   fi;

   # Case 1) we are now connected (ret=0) and we were previously outside (inside=1)
   if [ $ret -eq 0 ] && [ $inside -eq 1 ]
   then
      # change state to inside and do something (I am playing a song)
      inside=0
      mplayer /home/pi/documents/rasbpi/raspi1/media/audio/1.mp3 &>/dev/null
   # Case 2) we are no longer connected (ret=1) but we were previously inside (inside=0)
   elif [ $ret -eq 1 ] && [ $inside -eq 0 ]
   then
      # change state to outside and do something (I am playing another song)
      inside=1
      mplayer /home/pi/documents/rasbpi/raspi1/media/audio/2.mp3 &>/dev/null
   fi;
}

# run an infinite loop
while :
do
   phoneDetected $phone1
done

输出：

sudo rfcomm connect 0 AA:BB:CC:DD:EE:FF 10
echo $?

Connected /dev/rfcomm0 to AA:BB:CC:DD:EE:FF on channel 10
Press CTRL-C for hangup
0

sudo rfcomm connect 0 AA:BB:CC:DD:EE:FF 10
echo $?

Can't connect RFCOMM socket: Host is down
0

#!/bin/bash

phone1="AA:BB:CC:DD:EE:FF" #Address of phone
inside=1  # Whether the phone is 'inside' the house (0) or 'outside (1)

phoneDetected ()
{
   # Search for phone
   hcitool rssi $phone1 &>/dev/null
   ret=$?

   # If search was unsuccessful,
   if [ $ret -ne 0 ]
   then
      # Add phone
      sudo rfcomm connect 0 $phone1 10 &>/dev/null &

      # Note: the return code of rfcomm will almost always be 0,
      # so don't rely on it if you are looking for failed connections,
      # instead wait 5 seconds for rfcomm to connect, then check
      # connection again. Note this is not fool proof as an rfcomm
      # command taking longer than 5 seconds could break this program,
      # however, it generally only takes 2 seconds.
      sleep 5
      hcitool rssi $phone1 &>/dev/null
      ret=$?
   fi;

   # Case 1) we are now connected (ret=0) and we were previously outside (inside=1)
   if [ $ret -eq 0 ] && [ $inside -eq 1 ]
   then
      # change state to inside and do something (I am playing a song)
      inside=0
      mplayer /home/pi/documents/rasbpi/raspi1/media/audio/1.mp3 &>/dev/null
   # Case 2) we are no longer connected (ret=1) but we were previously inside (inside=0)
   elif [ $ret -eq 1 ] && [ $inside -eq 0 ]
   then
      # change state to outside and do something (I am playing another song)
      inside=1
      mplayer /home/pi/documents/rasbpi/raspi1/media/audio/2.mp3 &>/dev/null
   fi;
}

# run an infinite loop
while :
do
   phoneDetected $phone1
done

因为我试图确定手机何时在房间里，何时离开，所以我需要某种方法（其他方法）来检测加密狗何时可以连接到房间，何时不能连接到房间。我如何才能做到这一点？（注意：我试着把手机从大楼里拿出来，甚至把它完全关掉）

EDIT:我考虑捕获

stderr

消息并进行测试

error=$`sudo rfcomm connect 0 AA:BB:CC:DD:EE:FF 10 >/dev/null` &
if [ $error=="Can't connect RFCOMM socket: Host is down" ]
then
    ...
fi;

---

但问题是rfcomm必须在后台运行。

我还没有完全弄清楚如何做到这一点，但我就是这样解决的。在执行

sudo rfcomm connect 0 AA:BB:CC:DD:EE:FF 10

命令后，我只需等待5秒钟，然后检查是否存在连接。我怀疑这实际上是完美的，因为下一次迭代将捕获任何错误，但不要引用我的话。也许是更多的经验。我已经包括了最小工作示例（MWE），因此您可以遵循它

MWE:

sudo rfcomm connect 0 AA:BB:CC:DD:EE:FF 10
echo $?

Connected /dev/rfcomm0 to AA:BB:CC:DD:EE:FF on channel 10
Press CTRL-C for hangup
0

sudo rfcomm connect 0 AA:BB:CC:DD:EE:FF 10
echo $?

Can't connect RFCOMM socket: Host is down
0

#!/bin/bash

phone1="AA:BB:CC:DD:EE:FF" #Address of phone
inside=1  # Whether the phone is 'inside' the house (0) or 'outside (1)

phoneDetected ()
{
   # Search for phone
   hcitool rssi $phone1 &>/dev/null
   ret=$?

   # If search was unsuccessful,
   if [ $ret -ne 0 ]
   then
      # Add phone
      sudo rfcomm connect 0 $phone1 10 &>/dev/null &

      # Note: the return code of rfcomm will almost always be 0,
      # so don't rely on it if you are looking for failed connections,
      # instead wait 5 seconds for rfcomm to connect, then check
      # connection again. Note this is not fool proof as an rfcomm
      # command taking longer than 5 seconds could break this program,
      # however, it generally only takes 2 seconds.
      sleep 5
      hcitool rssi $phone1 &>/dev/null
      ret=$?
   fi;

   # Case 1) we are now connected (ret=0) and we were previously outside (inside=1)
   if [ $ret -eq 0 ] && [ $inside -eq 1 ]
   then
      # change state to inside and do something (I am playing a song)
      inside=0
      mplayer /home/pi/documents/rasbpi/raspi1/media/audio/1.mp3 &>/dev/null
   # Case 2) we are no longer connected (ret=1) but we were previously inside (inside=0)
   elif [ $ret -eq 1 ] && [ $inside -eq 0 ]
   then
      # change state to outside and do something (I am playing another song)
      inside=1
      mplayer /home/pi/documents/rasbpi/raspi1/media/audio/2.mp3 &>/dev/null
   fi;
}

# run an infinite loop
while :
do
   phoneDetected $phone1
done