You need to install libbluetooth-dev package for compiling your code

    sudo apt-get install libbluetooth-dev

That should install the bluetooth header files.

For Fedora, you can use:

    sudo dnf install bluez-libs-devel



On CentOS 7:

    sudo yum install bluez-libs-devel

When I run my program following a compile, I get the following error:

&gt; ./prog: /usr/lib/x86_64-linux-gnu/libstdc++.so.6: version `CXXABI_1.3.8&#39; not found (required by ./prog)
./prog: /usr/lib/x86_64-linux-gnu/libstdc++.so.6: version `GLIBCXX_3.4.19&#39; not found (required by ./prog)
./prog: /usr/lib/x86_64-linux-gnu/libstdc++.so.6: version `GLIBCXX_3.4.20&#39; not found (required by /home/arman/lib/boost_1_55_0/stage/lib/libboost_serialization.so.1.55.0)

I have both boost 1.55.0 and gcc 4.9.0 installed in `~/lib/boost_1_55_0` and `~/lib/gcc-4.9.0` respectively, and I&#39;m guessing this is why I&#39;m having problems, but I&#39;m unsure about how to go about fixing it.

my `~/.profile` contains the following line:

&gt; export LD_LIBRARY_PATH=/home/user/lib/boost_1_55_0/stage/lib:$LD_LIBRARY_PATH

version `CXXABI_1.3.8&#39; not found (required by ...)

How do I enable/disable anchor tags using the directive approach? 

Example: 

 1. while clicking on edit link, create &amp; delete needs to be disabled or grayed out
 2. while clicking on create link, edit &amp; delete needs to be disabled or grayed out

**JAVASCRIPT:**

        angular.module(&#39;ngApp&#39;, []).controller(&#39;ngCtrl&#39;,[&#39;$scope&#39;, function($scope){

        $scope.create = function(){
          console.log(&quot;inside create&quot;);
        };

        $scope.edit = function(){
          console.log(&quot;inside edit&quot;);
        };

        $scope.delete = function(){
        console.log(&quot;inside delete&quot;);
        };

        }]).directive(&#39;a&#39;, function() {
           return {
                restrict: &#39;E&#39;,
                link: function(scope, elem, attrs) {
                    if(attrs.ngClick || attrs.href === &#39;&#39; || attrs.href === &#39;#&#39;){
                        elem.on(&#39;click&#39;, function(e){
                            e.preventDefault();
                            if(attrs.ngClick){
                                scope.$eval(attrs.ngClick);
                            }
                        });
                    }
                }
           };
        }); 

[LINK to CODE][1]


  [1]: http://plnkr.co/edit/jQSnMfwVo8myeTwUciNU?p=preview

Enable/Disable Anchor Tags using AngularJS

I want to build a c file based on BlueZ but seems no bluetooth.h file in my system.

    fatal error: bluetooth/bluetooth.h: No such file or directory

I am sure the bluetooth dongle is running correctly and I have built Bluez successfully.

**Update**

For my case, I find the bluetooth.h in /user/include/bluetooth folder

Where is the bluetooth/bluetooth.h located in Linux?

I want to build a c file based on BlueZ but seems no bluetooth.h file in my system.
<pre><code class="hljs language-yaml">fatal error: bluetooth/bluetooth.h: No such file or directory
</code></pre>
I am sure the bluetooth dongle is running correctly and I have built Bluez successfully.
Update
For my case, I find the bluetooth.h in /user/include/bluetooth folder

GCC, MSVC, LLVM, and probably other toolchains have support for link-time (whole program) optimization to allow optimization of calls among compilation units.

Is there a reason not to enable this option when compiling production software?


Is there a reason why not to use link-time optimization (LTO)?

Is there a way to call C routines from Swift? 

A lot of iOS / Apple libraries are C only and I&#39;d still like to be able to call those.

For example, I&#39;d like to be able to call the objc runtime libraries from swift.

In particular, how do you bridge iOS C headers?

How to call C from Swift?

I know this sounds like a general question and I&#39;ve seen many similar questions (both here and on the web) but none of them are really like my dilemma.

Say I have this code:

    void GetSomeData(char* buffer)
    {
        // put some data in buffer
    }

    int main()
    {
         char buffer[1024];
         while(1)
         {
              GetSomeData(buffer);
              // do something with the data
         }
         return 0;
    }

Would I gain any performance if I declared buffer[1024] globally?

I ran some tests on unix via the time command and there are virtually no differences between the execution times.

But I&#39;m not really convinced...

In theory should this change make a difference?

Is accessing data in the heap faster than from the stack?

Like many other developers I have been very excited about the new Swift language from Apple. Apple has claimed its speed is faster than Objective C and can be used to write operating system. And from what I learned so far, it&#39;s a static typed language and able to have precisely control over the exact data type (like integer length). So it does look like having good potential handling performance critical tasks, like image processing, right?

That&#39;s what I thought before I carried out a quick test. The result really surprised me. 

Here is a simple code snippet in C:

test.c:

    #include &lt;stdio.h&gt;
    #include &lt;stdint.h&gt;
    #include &lt;string.h&gt;

    uint8_t pixels[640*480];
    uint8_t alpha[640*480];
    uint8_t blended[640*480];

    void blend(uint8_t* px, uint8_t* al, uint8_t* result, int size)
    {
        for(int i=0; i&lt;size; i++) {
            result[i] = (uint8_t)(((uint16_t)px[i]) *al[i] /255);
        }
    }

    int main(void)
    {
        memset(pixels, 128, 640*480);
        memset(alpha, 128, 640*480);
        memset(blended, 255, 640*480);

        // Test 10 frames
        for(int i=0; i&lt;10; i++) {
            blend(pixels, alpha, blended, 640*480);
        }

        return 0;
    }
          
I compiled it on my Macbook Air 2011 with the following command:
    
    clang -O3 test.c -o test

The 10 frame processing time is about 0.01s. In other words, it takes the C code 1ms to process one frame:

    $ time ./test
    real    0m0.010s
    user    0m0.006s
    sys     0m0.003s


Then I have a Swift version of the same code:

test.swift:

    let pixels = UInt8[](count: 640*480, repeatedValue: 128)
    let alpha = UInt8[](count: 640*480, repeatedValue: 128)
    let blended = UInt8[](count: 640*480, repeatedValue: 255)

    func blend(px: UInt8[], al: UInt8[], result: UInt8[], size: Int)
    {
        for(var i=0; i&lt;size; i++) {
            var b = (UInt16)(px[i]) * (UInt16)(al[i])
            result[i] = (UInt8)(b/255)
        }
    }

    for i in 0..10 {
        blend(pixels, alpha, blended, 640*480)
    }

The build command line is:

    xcrun swift -O3 test.swift -o test

Here I use the same `O3` level optimization flag to make the comparison hopefully fair. However, the resulting speed is 100 time slower:

    $ time ./test

    real    0m1.172s
    user    0m1.146s
    sys     0m0.006s

In other words, it takes Swift ~120ms to processing one frame which takes C just 1 ms. 

What happened?

&lt;h3&gt;Update: I am using clang:&lt;/h3&gt;

    $ gcc -v
    Configured with: --prefix=/Applications/Xcode6-Beta.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
    Apple LLVM version 6.0 (clang-600.0.34.4) (based on LLVM 3.5svn)
    Target: x86_64-apple-darwin13.2.0
    Thread model: posix

&lt;h3&gt; Update: more results with different running iterations: &lt;/h3&gt;
Here are the result for different number of &quot;frames&quot;, i.e. change the main `for` loop number from 10 to other numbers. Note now I am getting even faster C code time (cache hot?), while the Swift time doesn&#39;t change too much:

                 C Time (s)      Swift Time (s)
      1 frame:     0.005            0.130
     10 frames(*): 0.006            1.196
     20 frames:    0.008            2.397
    100 frames:    0.024           11.668

&lt;h3&gt; Update: `-Ofast` helps &lt;/h3&gt;
With `-Ofast` suggested by @mweathers, the Swift speed goes up to reasonable range.

On my laptop the Swift version with `-Ofast` gets 0.013s for 10 frames and 0.048s for 100 frames, close to half of the C performance. 



Why Swift is 100 times slower than C in this image processing test?

I&#39;m trying to get a C string returned by a C library and convert it to a Rust string via FFI.

**mylib.c**

&lt;!-- language: C --&gt;

    const char* hello(){
        return &quot;Hello World!&quot;;
    }

**main.rs**

&lt;!-- language: rust --&gt;

    #![feature(link_args)]
    
    extern crate libc;
    use libc::c_char;
    
    #[link_args = &quot;-L . -I . -lmylib&quot;]
    extern {
        fn hello() -&gt; *c_char;
    }
    
    fn main() {
        //how do I get a str representation of hello() here?
    }

How do I convert a C string into a Rust string and back via FFI?

Can&#39;t install python-dev on centos 6.5. Yum says &quot;No package python-dev available.&quot;. No graphical solutions please.

Can&#39;t install python-dev on centos 6.5

I&#39;m trying to write a Bash script that will overwrite an existing directory. I have a directory `foo/` and I am trying to overwrite `bar/` with it. But when I do this:

    cp -Rf foo/ bar/

a new `bar/foo/` directory is created. I don&#39;t want that. There are two files in `foo/`; `a` and `b`. There are files with same names in `bar/` as well. I want the `foo/a` and `foo/b` to replace `bar/a` and `bar/b`.


How to force &#39;cp&#39; to overwrite directory instead of creating another one inside?

I am writing a bash script that needs to parse filenames.

It will need to remove all special characters (including space): **&quot;!?.-_** and change all uppercase letters to lowercase.  Something like this:

    Some_randoM data1-A
    More Data0

to:

    somerandomdata1a
    moredata0

I have seen lots of questions to do this in many different programming languages, but not in bash.  Is there a good way to do this?

Remove all special characters and case from string in bash

I have bunch of files sitting in folders like

    data\A\A\A\json1.json
    data\A\A\A\json2.json
    data\A\A\B\json1.json
    ...
    data\Z\Z\Z\json_x.json

I want to cat all the jsons into one single file?


Recursively cat all the files into single file

I recently bought chinesse device that connects via bluetooth with android phone / tablet. Since there is no application availible for windows / linux I want to create one for personal usage.

Usually phone connects to the device and exchanges some data. I connected PC to the device and looked into serial debugger and menaged to discover the protocol (one way only). Phone sends only one command to the device. But this time I&#39;m not able to find out what it containts. 

Is there any software that will allow me to look into data sent via bluetooth? I tried decompiling the app, but it looks really unfriendly.

Thanks.



Sniffing/logging your own Android Bluetooth traffic

Using CoreBluetooth I want to send data from iPhone to Mac. For this I wrote code like iPhone as &#39;Peripheral&#39; and Mac as &#39;Central&#39;.
 
It works perfectly, but sometimes it disconnects directly and then it continuously connects and disconnects.
 
Some times when it is trying to reconnect, In Central it directly calls &#39;didDisconnectPeripheral&#39; delegate method. But some times it has error &quot;The handle is invalid&quot; in &#39;didUpdateNotificationStateForCharacteristic&#39;.
 
I referred all the links in net. But I am not able to solve this problem. I thought in iPhone it was storing Bluetooth cache.
 
Please suggest a solution how to solve &quot;The handle is invalid&quot; error?
 
 
Below are some of the important methods.
 
For Peripheral I wrote Code like below.
 
In Appdelegate:
 

    - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
    {
    self.peripheral = [[PeripheralServerObject alloc] init];
    self.peripheral.serviceUUID = [CBUUID UUIDWithString:@&quot;4w24&quot;];
    return YES;
    }

 
In Peripheral Object File:
 

    //To Check Bluetooth State
    - (void)peripheralManagerDidUpdateState:(CBPeripheralManager *)peripheral {
        switch (peripheral.state) {
            case CBPeripheralManagerStatePoweredOn:
                [self enableService];
                break;
            case CBPeripheralManagerStatePoweredOff: {
                [self disableService];
                break;
            }
    }
     
    // To Add characteristics to Service
    - (void)enableService
    {
    [self.peripheral removeAllServices];
     self.service = [[CBMutableService alloc]
                        initWithType:self.serviceUUID primary:YES];
                    
    self.authChar =
            [[CBMutableCharacteristic alloc] initWithType:[CBUUID UUIDWithString:@&quot;a86e&quot;]
                                               properties:CBCharacteristicPropertyNotify
                                                    value:nil
                                              permissions:CBAttributePermissionsReadable];
                                              
                                              
    self.respChar =
            [[CBMutableCharacteristic alloc] initWithType:[CBUUID UUIDWithString:@&quot;a86f&quot;]
                                               properties:CBCharacteristicPropertyWriteWithoutResponse
                                                    value:nil
                                              permissions:CBAttributePermissionsWriteable];
                                              
    self.service.characteristics = @[ self.authChar, self.respChar ];
     
        // Add the service to the peripheral manager.
        [self.peripheral addService:self.service];
    }
    
    //Peripheral Manager delegate method will be called after adding service.
    
    - (void)peripheralManager:(CBPeripheralManager *)peripheral
                didAddService:(CBService *)service
                        error:(NSError *)error {
        
        [self startAdvertising];
        
    }
     
    //To disable service 
    - (void)disableService
    {
     [self.peripheral stopAdvertising];
     [self.peripheral removeAllServices];
    }
     
    //To enable a service again.
    -(void)refreshService {
        [self disableService];
        [self enableService];
    }
     
     
    If central subscribes the characteristic, then the below peripheral delegate method will be called. In this I implemented code to send data
     
    - (void)peripheralManager:(CBPeripheralManager *)peripheral
                      central:(CBCentral *)central
    didSubscribeToCharacteristic:(CBCharacteristic *)characteristic {
      
        self.dataTimer = [NSTimer scheduledTimerWithTimeInterval:10.0
                                                          target:self
                                                        selector:@selector(sendData)
                                                        userInfo:nil
                                                         repeats:YES];
    }
     
    - (void)sendData
    {
    Here I am sending data like [Apple&#39;s BTLE Example Code][1]  
    }
     
    
    //If unsubscribed then I am invalidating timer and refreshing service
     
    - (void)peripheralManager:(CBPeripheralManager *)peripheral
                      central:(CBCentral *)central
    didUnsubscribeFromCharacteristic:(CBCharacteristic *)characteristic {
        
        if (self.dataTimer)
            [self.dataTimer invalidate];
        [self refreshService];
            
    }

 
For Mac I wrote a peripheral delegate methods.
 

    //I enables the notification for &quot;a860&quot; Characteristic.
     
    - (void)peripheral:(CBPeripheral *)peripheral
    didDiscoverCharacteristicsForService:(CBService *)service
    error:(NSError *)error {
     
         CBUUID * authUUID = [CBUUID UUIDWithString:@&quot;a86e&quot;];
           for (CBCharacteristic *characteristic in service.characteristics) {
     
            if ([characteristic.UUID isEqual:authUUID]) {
             }
            [self.connectedPeripheral setNotifyValue:YES
                                       forCharacteristic:characteristic];
             }
    }
     
    -(void)peripheral:(CBPeripheral *)peripheral didUpdateNotificationStateForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error {
       if (error) {
       Here I am getting error sometimes &quot;The handle is invalid&quot;.
        }
    }

 


  [1]: https://developer.apple.com/Library/ios/samplecode/BTLE_Transfer/Introduction/Intro.html

Setting Notifications on Characteristic results in Invalid Handle error

Connecting and disconnecting to Bluetooth devices has been giving various results on Windows Phone/Desktop 8.1. I have been using the `Windows.Devices.Bluetooth.Rfcomm` namespace and I have tried to connect several devices with different Bluetooth versions/classes.

* Version 1.2 (Class 1 and 2)
* Version 2.0 (Class 1 and 2)
* Version 2.1 (Class 1 and 2)
- Tested on Nokia Lumia 625 and Lumia 635, Dell Latitude E6500 and a Dell Precision M6400.

*Whenever I try to connect to either of the 2.0 or 2.1 devices there are issues. The first time I try to connect to each of the devices everything will go fine and the connection will open. When I subsequently close the connection and re-connect the device, the trouble starts.* 
During the re-connect the connection will never open and the debugger will throw a System.Exception :

    &gt; Message: No further data is available.

Also, when the connection fails the Windows 8.1 devices will keep trying to (unsuccessfully) connect to the Bluetooth Devices by themselves, even when my own application is terminated. Sometimes the Windows 8.1 device will also show the Bluetooth device as connected, while the device visually shows that it&#39;s not connected anymore. The only way to reconnect the Bluetooth device is to unpair it and shutdown/restart Bluetooth on the Windows device.

Whenever I try to make a new call to `DeviceInformation` after a failed connect it will refuse to return the device that I earlier tried to connect.

    &gt; Message: The service cannot be found in the specified name space.

Odd result, the 1.2 devices work perfectly.

Manifest File:

    &lt;m2:DeviceCapability Name=&quot;bluetooth.rfcomm&quot;&gt;
      &lt;m2:Device Id=&quot;any&quot;&gt;
        &lt;m2:Function Type=&quot;serviceId:00001101-0000-1000-8000-00805F9B34FB&quot;/&gt;
      &lt;/m2:Device&gt;
    &lt;/m2:DeviceCapability&gt;

Selecting Device:

    Guid RfcommChatServiceUuid = Guid.Parse(&quot;00001101-0000-1000-8000-00805F9B34FB&quot;);
    await DeviceInformation.FindAllAsync(RfcommDeviceService.GetDeviceSelector(RfcommServiceId.FromUuid(RfcommChatServiceUuid)));

Connecting:(id = chatserviceid)

    StreamSocket _socket;    
    RfcommDeviceService service = await RfcommDeviceService.FromIdAsync(deviceInformation1._id);
    await _socket.ConnectAsync(service.ConnectionHostName, service.ConnectionServiceName);

Disconnecting:

    this._socket.Dispose();
    this._socket = null;

I&#39;ve researched the MSDN, code samples, demo&#39;s, channel-9 video&#39;s and StackOverflow, no resource can tell me if there are issues with `Windows.Devices.Bluetooth.Rfcomm`.

Is there someone who recognizes these odd results? Am I doing something wrong? 

- [Similar problem was observed here][1]

- [Link to MSDN issue][2]

UPDATE: Working with Windows Phone 8.1 GDR2 is a possible solution. 

NOTE: For myself and several other people this update still gives the same issues.


  [1]: https://stackoverflow.com/questions/27122484/rfcomm-connection-works-unstable/
  [2]: https://social.msdn.microsoft.com/Forums/windowsapps/en-US/c2d2cc7a-b966-42b2-9c04-835b125b404e/disconnecting-bluetooth-devices-with-windowsdevicesbluetoothrfcomm?forum=wpdevelop

(Dis)Connecting bluetooth devices with Windows.Devices.Bluetooth.Rfcomm (WP8.1)

My project requires to receive&amp;send bluetooth signal, and I am pretty new to react-native so which component I can use in react-native for bluetooth related functionality?

Bluetooth in react-native

I have an android device acting as a hands free client device using hfp.

[Using the following code:][1] 

I am able to receive a call and the speakers and mic are working as expected.

My problem is that I can&#39;t seem to control the volume.


I tried using the following lines of code to find the correct stream, but none of them seem to work.

I tracked the volume command being sent from the phone to the client in the class `HeadsetClientStateMachine` , line #1822 in the following link: [HeadsetClientStateMachine from lolipop][2]

    case EVENT_TYPE_VOLUME_CHANGED:
        if (event.valueInt == HeadsetClientHalConstants.VOLUME_TYPE_SPK) {
            mAudioManager.setStreamVolume(AudioManager.STREAM_BLUETOOTH_SCO, event.valueInt2, AudioManager.FLAG_SHOW_UI);
            mVgsFromStack = true;
           Log.d(TAG, &quot;EventVolumeChange STREAM_BLUETOOTH_SCO value: &quot; + event.valueInt2);
        }

When I change the volume on the phone, I do see the log showing the updated value of the sound, which means that the `setStreamVolume()` method is being called, but the volume doesn&#39;t change.

Does anyone know what could be causing this issue?


**EDIT:**

I am still looking for an answer and am now looking toward the audio HAL implementation. I suspect that the link between the HAL and the audio driver is somehow incorrect... I don&#39;t know much about low level implementation and am not sure what I should be looking for.


  [1]: http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android-apps/5.0.0_r1/com/android/bluetooth/hfpclient/
  [2]: http://grepcode.com/file_/repository.grepcode.com/java/ext/com.google.android/android-apps/5.0.0_r1/com/android/bluetooth/hfpclient/HeadsetClientStateMachine.java/?v=source

Bluetooth hands free client volume control

How can I check the battery level of a connected bluetooth device? The device shows the battery level on Android so I&#39;m assuming the device supports the [GATT-based Battery Service][1]. However, by entering &quot;menu gatt&quot; in bluetoothctl and then listing the GATT attributes of the device with &quot;list-attributes [dev]&quot;, nothing shows up.

A [similar question was posted to SO][2] but the OP seems to have found a solution that doesn&#39;t work for me. When I run &quot;info [dev]&quot; in bluetoothctl I don&#39;t see the UUID for Battery Service.

I would prefer a solution that runs on the command line and is distro-agnostic.

Please let me know if this question should be posted on SuperUser instead.


  [1]: https://www.bluetooth.com/specifications/gatt/viewer?attributeXmlFile=org.bluetooth.service.battery_service.xml
  [2]: https://stackoverflow.com/questions/48058357/how-to-check-battery-level-of-a-bluetooth-paired-remote &quot;How to check battery level of a bluetooth paired remote&quot;

Content Type	Original Author	Original Content on Stackoverflow
Question	Yiding	View Question on Stackoverflow
Solution 1 - C	Rahul R Dhobi	View Answer on Stackoverflow
Solution 2 - C	Abishek Balu	View Answer on Stackoverflow
Solution 3 - C	SBF	View Answer on Stackoverflow

Where is the bluetooth/bluetooth.h located in Linux?

C Problem Overview

C Solutions

Solution 1 - C

Solution 2 - C

Solution 3 - C

Enable/Disable Anchor Tags using AngularJS

version `CXXABI_1.3.8' not found (required by ...)

Attributions