According to [the documentation][1], the Android kernel is missing quite a few of [the kernel features needed by LXC][2].

Perhaps in the future with Docker 1.x, it might be possible to write a plugin that uses Android features instead of LXC. But for now, you would need to build a custom Android kernel and then build LXC for it.

There are [some][3] [people][4] actually working on that, and [St&#233;phane Graber has a good summary of the difficulties on his blog][5].


  [1]: http://source.android.com/devices/tech/kernel.html
  [2]: http://lxc.sourceforge.net/man/lxc.html#AEN22
  [3]: http://www.linuxplumbersconf.org/2013/ocw/sessions/975
  [4]: https://funnel.hasgeek.com/droidcon2013/889-lxc-on-android-running-ics-and-jellybean-simultane
  [5]: https://www.stgraber.org/2013/12/23/lxc-1-0-some-more-advanced-container-usage/

It depends if this kernel is compiled with the required features to run containers. If it&#39;s the case, then Docker could be used on Android (especially Docker 0.7, which is in release candidate state right now, and doesn&#39;t require AUFS anymore).

I am working with `collections.Counter()` counters.  I would like to combine two of them in a meaningful manner.

Suppose I have 2 counters, say,  
    
    Counter({&#39;menu&#39;: 20, &#39;good&#39;: 15, &#39;happy&#39;: 10, &#39;bar&#39;: 5})

and
    
    Counter({&#39;menu&#39;: 1, &#39;good&#39;: 1, &#39;bar&#39;: 3})

I am trying to end up with:   
    
    Counter({&#39;menu&#39;: 21, &#39;good&#39;: 16, &#39;happy&#39;: 10,&#39;bar&#39;: 8})

How can I do this?

Summing the contents of two collections.Counter() objects

I have an app that connects to a MYSQL database through the entity framework. It works 100% perfectly, but I would like to add a small piece of code that will test the connection to the database upon app startup.

I had the idea of simply running a tiny command to the database and catching any exceptions, however if there is a problem (eg App.Config missing or Database server down) the app takes a huge amount of time to run this code and then throw the exception (~1 min). I imagine this is due to connection timeouts etc but I have fiddled with such properties to no avail.

Would anyone be able to assist with any ideas as to where to go?

Testing an Entity Framework database connection

With Android 4.4 KitKat, Google is upgrading linux kernel to version 3.8 which is the required kernel version for Docker.

I don&#39;t know the AUFS part but will there be a way to run docker containers on android with this update?

Running docker on Android

<p>With Android 4.4 KitKat, Google is upgrading linux kernel to version 3.8 which is the required kernel version for Docker.</p>
<p>I don't know the AUFS part but will there be a way to run docker containers on android with this update?</p>


We have used the YouTube API for android, but there is a problem with a fast closing and opening the same activity with the YouTube player and the YouTube player view. This problem appears in the sample application also, when I try to open `Fullscreen` activity (without clicking `fullscreenbutton`) then close activity with the back button and again and again. 

YouTube app is crashing like :
&gt;10-11 15:14:53.313: E/ActivityThread(22537): Activity com.example.myvideo.FullscreenDemoActivity has leaked ServiceConnection
com.google.android.youtube.player.internal.r$e@46095818 that was originally bound here

I have tried to override `OnStop` to release the player but with no positive result. Please somebody help!

`Fullscreen` activity modification - a few lines difference between original and this one :


    import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
    import static android.view.ViewGroup.LayoutParams.WRAP_CONTENT;
    import com.google.android.youtube.player.YouTubePlayer;
    import com.google.android.youtube.player.YouTubePlayer.PlayerStyle;
    import com.google.android.youtube.player.YouTubePlayerView;
    import android.content.Intent;
    import android.content.pm.ActivityInfo;
    import android.content.res.Configuration;
    import android.os.Build;
    import android.os.Bundle;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.Button;
    import android.widget.CompoundButton;
    import android.widget.LinearLayout;
    import android.widget.LinearLayout.LayoutParams;
    
    
    /**
     * Sample activity showing how to properly enable custom fullscreen behavior.
     * &lt;p&gt;
     * This is the preferred way of handling fullscreen because of the default fullscreen implementation
     * will cause re-buffering of the video.
     */
    public class FullscreenDemoActivity extends YouTubeFailureRecoveryActivity implements
            View.OnClickListener,
            CompoundButton.OnCheckedChangeListener,
            YouTubePlayer.OnFullscreenListener {
    
        private static final int PORTRAIT_ORIENTATION = Build.VERSION.SDK_INT &lt; 9
                ? ActivityInfo.SCREEN_ORIENTATION_PORTRAIT
                : ActivityInfo.SCREEN_ORIENTATION_SENSOR_PORTRAIT;
    
        private LinearLayout baseLayout;
        private YouTubePlayerView playerView;
        private YouTubePlayer player;
        private Button fullscreenButton;
        private CompoundButton checkbox;
        private View otherViews;
        public boolean CanClose = false;
        private boolean fullscreen;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            try {
                setContentView(R.layout.fullscreen_demo);
                baseLayout = (LinearLayout) findViewById(R.id.layout);
                playerView = (YouTubePlayerView) findViewById(R.id.player);
                fullscreenButton = (Button) findViewById(R.id.fullscreen_button);
                checkbox = (CompoundButton) findViewById(R.id.landscape_fullscreen_checkbox);
                otherViews = findViewById(R.id.other_views);
                checkbox.setOnCheckedChangeListener(this);
                // You can use your own button to switch to fullscreen too
                fullscreenButton.setOnClickListener(this);
                playerView.initialize(DeveloperKey.DEVELOPER_KEY, this);
                doLayout();
            } catch (Exception e) { }
        }
    
        @Override
        public void onInitializationSuccess(YouTubePlayer.Provider provider, YouTubePlayer player, boolean wasRestored) {
            try {
                this.player = player;
                player.setPlayerStyle(PlayerStyle.MINIMAL);
                //player.setShowFullscreenButton(true);
                setControlsEnabled();
                // Specify that we want to handle fullscreen behavior ourselves.
                player.addFullscreenControlFlag(YouTubePlayer.FULLSCREEN_FLAG_CUSTOM_LAYOUT);
                player.setOnFullscreenListener(this);
                if (!wasRestored) {
                    player.cueVideo(MainActivity.CurrentVideo);
                }
            } catch (Exception e) { }
        }
    
        @Override
        protected YouTubePlayer.Provider getYouTubePlayerProvider() {
            return playerView;
        }
    
        @Override
        public void onClick(View v) {
            player.setFullscreen(!fullscreen);
        }
    
        @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
            try {
                int controlFlags = player.getFullscreenControlFlags();
                if (isChecked) {
                    // If you use the FULLSCREEN_FLAG_ALWAYS_FULLSCREEN_IN_LANDSCAPE, your activity&#39;s normal UI
                    // should never be laid out in landscape mode (since the video will be fullscreen whenever the
                    // activity is in landscape orientation). Therefore you should set the activity&#39;s requested
                    // orientation to portrait. Typically you would do this in your AndroidManifest.xml, we do it
                    // programmatically here since this activity demos fullscreen behavior both with and without
                    // this flag).
                    setRequestedOrientation(PORTRAIT_ORIENTATION);
                    controlFlags |= YouTubePlayer.FULLSCREEN_FLAG_ALWAYS_FULLSCREEN_IN_LANDSCAPE;
                } else {
                    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_SENSOR);
                    controlFlags &amp;= ~YouTubePlayer.FULLSCREEN_FLAG_ALWAYS_FULLSCREEN_IN_LANDSCAPE;
                }
                player.setFullscreenControlFlags(controlFlags);
            } catch (Exception e) { }
        }
    
        private void doLayout() {
            try {
                LinearLayout.LayoutParams playerParams = (LinearLayout.LayoutParams) playerView.getLayoutParams();
                if (fullscreen) {
                    // When in fullscreen, the visibility of all other views than the player should be set to
                    // GONE and the player should be laid out across the whole screen.
                    playerParams.width = LayoutParams.MATCH_PARENT;
                    playerParams.height = LayoutParams.MATCH_PARENT;
                    otherViews.setVisibility(View.GONE);
                } else {
                    // This layout is up to you - this is just a simple example (vertically stacked boxes in
                    // portrait, horizontally stacked in landscape).
                    otherViews.setVisibility(View.VISIBLE);
                    ViewGroup.LayoutParams otherViewsParams = otherViews.getLayoutParams();
                    if (getResources().getConfiguration().orientation == Configuration.ORIENTATION_LANDSCAPE) {
                        playerParams.width = otherViewsParams.width = 0;
                        playerParams.height = WRAP_CONTENT;
                        otherViewsParams.height = MATCH_PARENT;
                        playerParams.weight = 1;
                        baseLayout.setOrientation(LinearLayout.HORIZONTAL);
                    } else {
                        playerParams.width = otherViewsParams.width = MATCH_PARENT;
                        playerParams.height = WRAP_CONTENT;
                        playerParams.weight = 0;
                        otherViewsParams.height = 0;
                        baseLayout.setOrientation(LinearLayout.VERTICAL);
                    }
                    setControlsEnabled();
                }
            } catch (Exception e) { }
        }
    
        private void setControlsEnabled() {
            checkbox.setEnabled(player != null &amp;&amp;
                    getResources().getConfiguration().orientation == Configuration.ORIENTATION_PORTRAIT);
            fullscreenButton.setEnabled(player != null);
        }
    
        @Override
        public void onFullscreen(boolean isFullscreen) {
            fullscreen = isFullscreen;
            doLayout();
        }
    
        @Override
        public void onConfigurationChanged(Configuration newConfig) {
            super.onConfigurationChanged(newConfig);
            doLayout();
        }
    
        @Override
        public void onStop() {
            if (player != null) {
                player.release();
                player = null;
            }
            super.onStop();
        }
    
        @Override
        public void finish() {
            Intent data = new Intent();
            setResult(RESULT_OK, data);
            super.finish();
        }
    }

Android Youtube Player API activity finish and create

I am trying to do a tab layout same in Play Store. I got to display the [tab layout using a fragments and viewpager from androidhive.][1] However, I can&#39;t implement [google maps v2][2] on it. I searched the internet for hours already, but I can&#39;t find a tutorial on how to do it. Can some one please show me how?


  [1]: http://www.androidhive.info/2013/10/android-tab-layout-with-swipeable-views-1/
  [2]: http://wptrafficanalyzer.in/blog/driving-distance-and-travel-time-duration-between-two-locations-in-google-map-android-api-v2/

How to put Google Maps V2 on a Fragment using ViewPager

I am creating a `TextView` with a drawable underneath, in a `GridLayout`. 

I want to bring the drawable to the middle of the `TextView`; I tried with 
`setCompoundDrawablePadding(-75)` and it only changes the position of the text.

Current code:

        TextView secondItem = new TextView(this);
        GridLayout.LayoutParams second = new GridLayout.LayoutParams(row2, col1);
        second.width = halfOfScreenWidth;
        second.height = (int) (quarterScreenWidth * 1.5);
        secondItem.setLayoutParams(second);
        secondItem.setBackgroundResource(R.color.MenuSecond);
        secondItem.setCompoundDrawablesRelativeWithIntrinsicBounds(0, 0, 0, R.drawable.ic_action_new);
        secondItem.setText(&quot;Text&quot;);
        secondItem.setCompoundDrawablePadding(-180);
        secondItem.setGravity(Gravity.CENTER);
        secondItem.setTextAppearance(this, android.R.style.TextAppearance_Large_Inverse);
        gridLayout.addView(secondItem, second);
            

How can I set the text and drawable to the middle of the `TextView`?

Android TextView drawable, change padding between drawable and text?

I want to reset `Android Studio 0.2.13` to the default state. That means reset all settings, remove all projects, all gradle files so that it would act like a fresh installation. What steps do I have to follow to achieve this?

How to reset Android Studio

I recently read this article on *[Managing Your App&#39;s Memory][1]*,I strongly suggest to read it if you are an AndroidDev and never did.

There are lots of good practices and one thing I never happen to know about is the [onTrimMemory(int level)][2] method called by the system on every Activity/Fragment to notify events on which memory should or could be released.

Here is a quote from that article:

&gt; **Notice that your app receives the onTrimMemory() callback with
&gt; TRIM_MEMORY_UI_HIDDEN only when all the UI components of your app
&gt; process become hidden from the user**. This is distinct from the
&gt; onStop() callback, which is called when an Activity instance becomes
&gt; hidden, which occurs even when the user moves to another activity in
&gt; your app. So although you should implement onStop() to release
&gt; activity resources such as a network connection or to unregister
&gt; broadcast receivers, **you usually should not release your UI resources
&gt; until you receive onTrimMemory(TRIM_MEMORY_UI_HIDDEN)**. This ensures
&gt; that if the user navigates back from another activity in your app,
&gt; your UI resources are still available to resume the activity quickly.


I am really interested in implementing a good memory management in my application so I am looking forward to implement the [onTrimMemory()][3] in the right way.

I only have a few questions about it:

 - is [onTrimMemory(TRIM_MEMORY_UI_HIDDEN)][4] called right after the onStop()?


 - what &quot;release your UI resources&quot; means in that context? just for instance clean the Bitmap cache, or actually remove and destroy every View in the View tree? i usually destroy the Views in the *onDestroy()* or *onDestroyView()* methods, i am now wondering if i&#39;m doing it right.


 - is there a Twin/correspondent callback to [onTrimMemory(TRIM_MEMORY_UI_HIDDEN)][5]? like *onCreate-onDestroy*, *onStart-onStop*, *onCreateView-onDestroyView*. I&#39;m asking to understand where and how i should restore the UI state after an Activity/Fragment as been brought in foreground after [onTrimMemory(TRIM_MEMORY_UI_HIDDEN)][6] has been called.


  [1]: http://developer.android.com/training/articles/memory.html
  [2]: http://developer.android.com/reference/android/content/ComponentCallbacks2.html#onTrimMemory%28int%29
  [3]: http://developer.android.com/reference/android/content/ComponentCallbacks2.html#onTrimMemory%28int%29
  [4]: http://developer.android.com/reference/android/content/ComponentCallbacks2.html#onTrimMemory%28int%29
  [5]: http://developer.android.com/reference/android/content/ComponentCallbacks2.html#onTrimMemory%28int%29
  [6]: http://developer.android.com/reference/android/content/ComponentCallbacks2.html#onTrimMemory%28int%29

understanding onTrimMemory( int level )

I am trying to get a specific line from a text file.

So far, online I have only seen stuff like sed, (I can only use the sh -not bash or sed or anything like that). I need to do this only using a basic shell script.

    cat file | while read line
    	do
    	   #do something
    	done

I know how to iterate through lines, as shown above, but what if I just need to get the contents of a particular line


Get specific line from text file using just shell script

I have a new Ubuntu 12.04 VPS. I am trying to write a setup script that completes an entire LAMP installation. Where I am having trouble is appending a line to the `/etc/hosts` file. My current hosts file looks like this:

    127.0.0.1       localhost Venus

    # The following lines are desirable for IPv6 capable hosts
    ::1     ip6-localhost ip6-loopback
    fe00::0 ip6-localnet
    ff00::0 ip6-mcastprefix
    ff02::1 ip6-allnodes
    ff02::2 ip6-allrouters

I would like it to look like this:

    127.0.0.1       localhost Venus
    192.241.xx.xx  venus.example.com venus

    # The following lines are desirable for IPv6 capable hosts
    ::1     ip6-localhost ip6-loopback
    fe00::0 ip6-localnet
    ff00::0 ip6-mcastprefix
    ff02::1 ip6-allnodes
    ff02::2 ip6-allrouters

I have tried a variety of `sed` commands using the append (`\a`) command. For some reason Ubuntu either just echoes the contents of the `hosts` file in terminal or does nothing at all. How would I properly inject the second line into the file with a bash script?

Append line to /etc/hosts file with shell script

I&#39;m trying to compile this source code from the makefile in a VPS, but its not working. The VPS is a 64 Cent OS

Here&#39;s the full error

    # make
    gcc -c -O3 -w -DLINUX -I../SDK/amx/ ../SDK/amx/*.c
    g++ -c -O3 -w -DLINUX -I../SDK/amx/ ../SDK/*.cpp
    g++ -c -O3 -w -DLINUX -I../SDK/amx/ *.cpp
    g++ -O2 -fshort-wchar -shared -o &quot;TCP_V1.so&quot; *.o
    /usr/bin/ld: TCP-LINUX_V1.o: relocation R_X86_64_32 against `.rodata.str1.8&#39; can not be     used when making a shared object; recompile with -fPIC
    TCP-LINUX_V1.o: could not read symbols: Bad value
    collect2: ld returned 1 exit status
    make: *** [all] Error 1

Here&#39;s my makefile:

    GPP=g++
    GCC=gcc
    OUTFILE=&quot;TCP_V1.so&quot;

    COMPILE_FLAGS=-c -O3 -w -DLINUX -I../SDK/amx/

    all:
	    $(GCC) $(COMPILE_FLAGS) ../SDK/amx/*.c
	    $(GPP) $(COMPILE_FLAGS) ../SDK/*.cpp
	    $(GPP) $(COMPILE_FLAGS) *.cpp
	    $(GPP) -O2 -fshort-wchar -shared -o $(OUTFILE) *.o

Anyone know what&#39;s wrong?


Compilation fails with &quot;relocation R_X86_64_32 against `.rodata.str1.8&#39; can not be used when making a shared object&quot;

So I&#39;m now desperate in finding a fix for this. I&#39;m compiling a shared library .so in Ubuntu 32 bit (Have tried doing it under Debian and Ubuntu 64 bit, but none worked either)

I keep getting: `/usr/lib/libstdc++.so.6: version ``GLIBCXX_3.4.15&#39; not found` every time I try to load my plugin.

Here&#39;s how I&#39;m getting this error:

1. Install latest Ubuntu 32 bit
2. sudo apt-get install build-essential
3. Compile &amp; load my plugin (.so)

Here are some links which I found and tried, but none worked for me:

(My old question: I somehow got it fixed a few days after posting this question, but I can&#39;t remember how exactly I did it) 

[My Question][1]

[Another user with the same problem][2]

[And another][3]

I see some people fixed it by moving libstdc++(i think) to some directory and then pointing or linking idk what to that directory, but that just puzzled me.


Anyone know a fix?


(Edit:)
- Running: `strings /usr/lib/libstdc++.so.6 | grep GLIBC` in terminal gives me: `strings &#39;/usr/lib/libstdc++.so.6&#39;: No such file`. Could that be the problem? And if so, how do I install this library?


  [1]: https://stackoverflow.com/questions/12444136/what-does-usr-lib-libstdc-so-6-version-glibcxx-3-4-15-not-found-mean-and
  [2]: https://stackoverflow.com/questions/5216399/usr-lib-libstdc-so-6-version-glibcxx-3-4-15-not-found
  [3]: https://bbs.archlinux.org/viewtopic.php?pid=1065388

(Edit2:) Anyone else know of a solution?

(Edit3) Still in need of a solution. is there a way to see on which distro a shared library was compiled on? I know I once compiled this same library a while ago, but can&#39;t remember!!

(Edit4) `ldd my_lib_.so` gives me:

        linux-gate.so.1 =&gt;  (0xb77d7000)
        libstdc++.so.6 =&gt; /usr/lib/i386-linux-gnu/libstdc++.so.6 (0xb76c1000)
        libgcc_s.so.1 =&gt; /lib/i386-linux-gnu/libgcc_s.so.1 (0xb76a4000)
        libc.so.6 =&gt; /lib/i386-linux-gnu/libc.so.6 (0xb74fa000)
        libm.so.6 =&gt; /lib/i386-linux-gnu/libm.so.6 (0xb74ce000)
        /lib/ld-linux.so.2 (0xb77d8000)

`ldd program_im_loading_so_into` gives me:

        linux-gate.so.1 =&gt;  (0xb77d8000)
        libdl.so.2 =&gt; /lib/i386-linux-gnu/libdl.so.2 (0xb77c0000)
        libpthread.so.0 =&gt; /lib/i386-linux-gnu/libpthread.so.0 (0xb77a5000)
        libstdc++.so.6 =&gt; /usr/lib/i386-linux-gnu/libstdc++.so.6 (0xb76bb000)
        libm.so.6 =&gt; /lib/i386-linux-gnu/libm.so.6 (0xb768f000)
        libgcc_s.so.1 =&gt; /lib/i386-linux-gnu/libgcc_s.so.1 (0xb7672000)
        libc.so.6 =&gt; /lib/i386-linux-gnu/libc.so.6 (0xb74c9000)
        /lib/ld-linux.so.2 (0xb77d9000)

running `strings /usr/lib/i386-linux-gnu/libstdc++.so.6 | grep GLIBCXX` gives me:

    GLIBCXX_3.4
    GLIBCXX_3.4.1
    GLIBCXX_3.4.2
    GLIBCXX_3.4.3
    GLIBCXX_3.4.4
    GLIBCXX_3.4.5
    GLIBCXX_3.4.6
    GLIBCXX_3.4.7
    GLIBCXX_3.4.8
    GLIBCXX_3.4.9
    GLIBCXX_3.4.10
    GLIBCXX_3.4.11
    GLIBCXX_3.4.12
    GLIBCXX_3.4.13
    GLIBCXX_3.4.14
    GLIBCXX_3.4.15
    GLIBCXX_3.4.16
    GLIBCXX_3.4.17
    GLIBCXX_3.4.18
    GLIBCXX_3.4.19
    GLIBCXX_DEBUG_MESSAGE_LENGTH

and finally here&#39;s my gcc version:

    `gcc version 4.6.4 (Ubuntu/Linaro 4.6.4-1ubuntu1~12.04)`

How to fix: /usr/lib/libstdc++.so.6: version `GLIBCXX_3.4.15&#39; not found

How do you grep and only return the matching line? i.e. The path/filename is omitted from the results.

In this case I want to look in all .bar files in the current directory, searching for the term FOO

    find . -name &#39;*.bar&#39; -exec grep -Hn FOO {} \;

grep without showing path/file:line

I did `sudo cat /proc/1/maps -vv`

I am attempting to make sense of the output.I can see a lot of shared libraries being mapped to the memory mapping segment as expected.

    7f3c00137000-7f3c00179000 r-xp 00000000 08:01 21233923                   /lib/x86_64-linux-gnu/libdbus-1.so.3.5.8
    7f3c00179000-7f3c00379000 ---p 00042000 08:01 21233923                   /lib/x86_64-linux-gnu/libdbus-1.so.3.5.8
    7f3c00379000-7f3c0037a000 r--p 00042000 08:01 21233923                   /lib/x86_64-linux-gnu/libdbus-1.so.3.5.8
    7f3c0037a000-7f3c0037b000 rw-p 00043000 08:01 21233923                   /lib/x86_64-linux-gnu/libdbus-1.so.3.5.8
    7f3c0037b000-7f3c00383000 r-xp 00000000 08:01 21237216                   /lib/x86_64-linux-gnu/libnih-dbus.so.1.0.0
    7f3c00383000-7f3c00583000 ---p 00008000 08:01 21237216                   /lib/x86_64-linux-gnu/libnih-dbus.so.1.0.0
    7f3c00583000-7f3c00584000 r--p 00008000 08:01 21237216                   /lib/x86_64-linux-gnu/libnih-dbus.so.1.0.0
    7f3c00584000-7f3c00585000 rw-p 00009000 08:01 21237216                   /lib/x86_64-linux-gnu/libnih-dbus.so.1.0.0
    7f3c00585000-7f3c0059b000 r-xp 00000000 08:01 21237220                   /lib/x86_64-linux-gnu/libnih.so.1.0.0
    7f3c0059b000-7f3c0079b000 ---p 00016000 08:01 21237220                   /lib/x86_64-linux-gnu/libnih.so.1.0.0
    7f3c0079b000-7f3c0079c000 r--p 00016000 08:01 21237220                   /lib/x86_64-linux-gnu/libnih.so.1.0.0

Towards the end there is something like

    7f3c0165b000-7f3c0177e000 rw-p 00000000 00:00 0                          [heap]
    7fff97863000-7fff97884000 rw-p 00000000 00:00 0                          [stack]
    7fff97945000-7fff97946000 r-xp 00000000 00:00 0                          [vdso]
    ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0                  [vsyscall]

What does `vdso` and `vsyscall` mean? is vsyscall the kernel portion of the memory? It would be great if anyone can throw some light on the issue.



What are vdso and vsyscall?

While debugging `C++` code in Qt creator I get the following error

    ptrace: Operation not permitted.
    
    Could not attach to the process. Make sure no other debugger traces this process.
    Check the settings of
    /proc/sys/kernel/yama/ptrace_scope
    For more details, see /etc/sysctl.d/10-ptrace.conf

Here a temporary solution is found: [Receiving error while trying to debug in QtProject][1]

 - temporary solution (won&#39;t survive a reboot):

     `echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope`


But it is difficult to run the same code in terminal every time when I start my PC to use Qt. 

    What is the permanent solution for this?

  [1]: https://askubuntu.com/questions/244336/receiving-error-while-trying-to-debug-in-qtproject


Qt Creator, ptrace: Operation not permitted. What is the permanent solution?

What is the difference between them?

I know that u-boot needs a kernel in uImage format.

The system I use first boots from stage 1 loader and then it calls u-boot. I want to discard u-boot and directly boot from stage 1 loader. Which type of kernel image do I have to use? 

Image vs zImage vs uImage

I need to write an SPI Linux character device driver for omap4 from scratch.
I know some basics of writing device drivers. But, I don&#39;t know how to start writing platform specific device driver from scratch.

I&#39;ve written some basic char drivers, and I thought writing SPI device driver would be similar to it. Char drivers have a structure `file_operations` which contains the functions implemented in the driver.

    struct file_operations Fops = {
    	.read = device_read,
    	.write = device_write,
    	.ioctl = device_ioctl,
    	.open = device_open,
    	.release = device_release,	/* a.k.a. close */
    };

Now, I am going through [spi-omap2-mcspi.c][1] code as a reference to get an idea to start developing SPI driver from scratch.

But, I don&#39;t see functions such as open, read, write etc.
Don&#39;t know from where the program starts.


  [1]: http://lxr.free-electrons.com/source/drivers/spi/spi-omap2-mcspi.c

How to write a simple Linux device driver?

I read a paper and it used terms **cold cache** and **warm cache**. I googled about this terms but I didn&#39;t find something useful (only a thread [here][1]). 

What do these terms mean? 



  [1]: https://web.archive.org/web/20150420002300/http://help.lockergnome.com/linux/Cold-cache-warm-cache--ftopict414393.html

What does it mean by cold cache and warm cache concept?

I&#39;m not sure if I&#39;ve misunderstood something here, but it seems like it&#39;s only possible to set port mappings by creating a new container from an image. Is there a way to assign a port mapping to an existing Docker container?


How do I assign a port mapping to an existing Docker container?

I&#39;m building a container for a ruby app. My app&#39;s configuration is contained within environment variables (loaded inside the app with [dotenv](http://github.com/bkeepers/dotenv)).

One of those configuration variables is the public ip of the app, which is used internally to make links.
I need to add a dnsmasq entry pointing this ip to 127.0.0.1 inside the container, so it can fetch the app&#39;s links as if it were not containerized.

I&#39;m therefore trying to set an `ENV` in my Dockerfile which would pass an environment variable to the container.

I tried a few things.

    ENV REQUEST_DOMAIN $REQUEST_DOMAIN
    ENV REQUEST_DOMAIN `REQUEST_DOMAIN`

Everything passes the &quot;REQUEST_DOMAIN&quot; string instead of the value of the environment variable though.
Is there a way to pass environment variables values from the host machine to the container?

Get environment variable value in Dockerfile

Despite Docker&#39;s [Interactive tutorial][1] and [faq][2] I lose my data when the container exits.

I have installed Docker as described here: http://docs.docker.io/en/latest/installation/ubuntulinux
without any problem on ubuntu 13.04.

But it loses all data when exits.

    iman@test:~$ sudo docker version
    Client version: 0.6.4 
    Go version (client): go1.1.2 
    Git commit (client): 2f74b1c 
    Server version: 0.6.4 
    Git commit (server): 2f74b1c 
    Go version (server): go1.1.2 
    Last stable version: 0.6.4 
    
    
    iman@test:~$ sudo docker run ubuntu ping
    2013/10/25 08:05:47 Unable to locate ping 
    iman@test:~$ sudo docker run ubuntu apt-get install ping
    Reading package lists... 
    Building dependency tree... 
    The following NEW packages will be installed: 
      iputils-ping 
    0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. 
    Need to get 56.1 kB of archives. 
    After this operation, 143 kB of additional disk space will be used. 
    Get:1 http://archive.ubuntu.com/ubuntu/ precise/main iputils-ping amd64 3:20101006-1ubuntu1 [56.1 kB] 
    debconf: delaying package configuration, since apt-utils is not installed 
    Fetched 56.1 kB in 0s (195 kB/s) 
    Selecting previously unselected package iputils-ping. 
    (Reading database ... 7545 files and directories currently installed.) 
    Unpacking iputils-ping (from .../iputils-ping_3%3a20101006-1ubuntu1_amd64.deb) ... 
    Setting up iputils-ping (3:20101006-1ubuntu1) ... 
    iman@test:~$ sudo docker run ubuntu ping
    2013/10/25 08:06:11 Unable to locate ping 
    iman@test:~$ sudo docker run ubuntu touch /home/test
    iman@test:~$ sudo docker run ubuntu ls /home/test
    ls: cannot access /home/test: No such file or directory 

I also tested it with interactive sessions with the same result. Did I forget something?


  [1]: http://www.docker.io/gettingstarted/
  [2]: http://docs.docker.io/en/latest/faq/#do-i-lose-my-data-when-the-container-exits



EDIT: IMPORTANT FOR NEW DOCKER USERS
------------------------------------
As @mohammed-noureldin and others said, actually this is **NOT** a **container exiting**. Every time it just creates a new container.

I lose my data when the container exits

I can attach to a docker process but &lt;kbd&gt;Ctrl&lt;/kbd&gt;+&lt;kbd&gt;c&lt;/kbd&gt; doesn&#39;t work to detach from it. `exit` basically halts the process. 

What&#39;s the recommended workflow to have the process running, occasionally attaching to it to make some changes, and then detaching?

How do you attach and detach from Docker&#39;s process?

I&#39;m trying to create a Docker container that acts like a full-on virtual machine. I know I can use the EXPOSE instruction inside a Dockerfile to expose a port, and I can use the `-p` flag with `docker run` to assign ports, but once a container is actually running, is there a command to open/map additional ports live?

For example, let&#39;s say I have a Docker container that is running sshd. Someone else using the container ssh&#39;s in and installs httpd. Is there a way to expose port 80 on the container and map it to port 8080 on the host, so that people can visit the web server running in the container, without restarting it?


Content Type	Original Author	Original Content on Stackoverflow
Question	Xelom	View Question on Stackoverflow
Solution 1 - Android	Rohan Singh	View Answer on Stackoverflow
Solution 2 - Android	jpetazzo	View Answer on Stackoverflow

Running docker on Android

Android Problem Overview

Android Solutions

Solution 1 - Android

Solution 2 - Android

Testing an Entity Framework database connection

Summing the contents of two collections.Counter() objects

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