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Linux no sound after boot into Windows

Just now was trying to boot into Windows, by plugged in the HDMI cable, which supports for video only. But then, I rebooted into Linux without plugged out the HDMI cable. Then, it caused no sound in Linux.

Try 1: I killed the pulseaudio, then delete the ~/.config/pulse, and rebooted Linux. Failed.

Try 2: Run alsamixer, turned on everything, and do Try 1 again. Failed.

Then I guessed it was caused by the HDMI cable, which the Windows may assume there is audio, then caused my computer somehow ouptut the audio through the HDMI, even I rebooted into Linux.

Try 3: Plugged out the HDMI, booted into Windows. I checked the audio in Windows. It plays well. Then rebooted into Linux without plugged in HDMI. Yeah! It works. Passed.

Next level

Then I found that, though the sound works fine, my headphones doesn’t work. Tried out many methods as I asked in forum.

At the end, it is solved by shutdown, and boot again.

Arch Linux update issue

Today, when I updated Arch Linux as usual, then suddenly it brought me to the TTY, which didn’t allow me to change to other TTY (due to NVIDIA graphic card issue which has been attached with my laptop for quite a long time.)

Because I could do nothing, and not sure whether the upgrade was completed, so I made a hard reset.

Then I boot with fallback initrmfs just in case has any error. Luckily, there was no problem to boot.

Then I did a quick check on the database. And found that it was locked. Meaning, I had restarted without finishing the update. This is serious if it happened when upgrading the kernel.

Reading the /var/log/pacman.log, I found that some packages were not updated. Then I just simply did a pacman command, and I got these message,

ldconfig: File /usr/lib/ is empty, not checked.
ldconfig: File /usr/lib/ is empty, not checked.
ldconfig: File /usr/lib/ is empty, not checked.

Read the forum, the solution to re-install the packages that own these files. So I used pkgfile to search fo the owner of these files. Then, re-installed each packages found.

Then I just made sure all the packages were installed properly with

pacman -Dk #previously is testdb

Social media

Different social media usage:

Facebook – Family and friends status.

Google+ – Official tech news or blogs.

Twitter – Celebrities personal status.

Weibo – China celebrities personal status.

Instagram – Celebrities’ photos.

Reddit – Community and specific topic discussion.

WordPress – Nothing but blog posts.

C++ revisit

I liked C programming, as it is low level and the compiler is widely available. Using C language can demonstrate the understanding of pointer and memory. You can implement a linked list or a hash table by using C. So that you can understand better how the linked list and hash table work.

But as long as you want to build some end user applications, C language is never a good choice. Choosing a language for our product is important. We do not develop a web application using low level programming language. It is totally impractical.

C and C++

Do not think that C language is an old language. It can survive until today because it has some powerful features (yet I cannot name them out, because I am not a C developer). There are new features on C99 and C11. But practically to solve higher level problem like game development, C++ is much more better than C. (But there is a better choice like Lua.)


Why is C++ better than C? From the syntax level, it is easier to read and easier to write. For example,


where myString is a C string, then trim() is a function that returns trimmed string, strtolower() is another function that returns the string with lower case. (The function names I used here is based on PHP.) So, we can see, when we read or write, we need to read from right to left: trim then strtolower. And the parentheses needs to be matched properly.

On the other hand for C++,


Let’s say myString is a customized object, namely MyString, that manipulates the string. So, the syntax is much more intuitive. myString calls the trim() method and returns the MyString object, so that we can continue with strtolower() that returns MyString object. This is called method chaining.

Object oriented

Object oriented is a wondrous invention! It is so powerful that most programming languages today support object oriented. Inheritance, polymorphoism, and interface, these features reduce a lot of tremendous works. You can implement object oriented in C (using library such as GObject), but C language is not designed for object oriented.

Because of syntax and the object oriented, I prefer C++ than C.


Another advantage of C++ is the string. C string is an array of character, with the fixed size. It is not dynamic as C++ string. For example, you want to perform strcat(), you need to have a larger buffer to store the strcat() result. And if you want to do it with dynamic memory allocation, then you have to free the memory manually. This is exhaustive.

Object method

Related to method chaining, in C++ we can write the methods. In C, because it is using struct, to implement something like method is troublesome. For example,

#include <stdio.h>
#include <stdlib.h>

typedef struct {
    int a;
    int (*b)(int a);
} MyType;

int myTypeMethod(int a) {
    return a+20;

MyType* myTypeNew() {
    MyType* myType = (MyType*)malloc(sizeof(MyType));
    myType->a = 20;
    myType->b = myTypeMethod; //There is no method in struct, so we assign the callback function
    return myType;

void myTypeDelete(MyType** myType) {
    *myType = NULL;

int main(int argc, char** argv) {
    MyType* myType = myTypeNew();
    printf("%d\n", myType->a);
    printf("%d\n", myType->b(20));
    return 0;

Because C doesn’t have namespace, but we can do something like namespace by using prefix.

C++11, C++14, C++1z

If you are not C++ lover, you may think that C++ is an archaic programming language. Just like HTML and JavaScript, there are ongoing proposals for the new features for C++. That is why, C++ is not dying yet. There are some notable features I need to state here.

New syntax

“auto” data type

#include <iostream>
#include <typeinfo>
using namespace std;

int main(int argc, char** argv) {
  int a = 10;
  auto b = a;
  cout << b << endl;
  cout << typeid(b).name() << endl; //"i" as integer
  float c = 20.0f;
  b = c;
  cout << b << endl;
  cout << typeid(b).name() << endl; //Still "i"
  return 0;

“auto” is just like “var” in C#.


Most modern programming languages allows foreach keyword, like JavaScript, PHP, and even Python. Though Python uses “for” keyword, it works actually like foreach in PHP.

#include <iostream>
using namespace std;
int main(int argc, char** argv) {
  int a[] = { 4, 5, 3, 2, 1 };
  for(auto item : a) {
    cout << item << endl;
  return 0;

Another foreach,

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main(int argc, char** argv) {
  vector<int> a{ 4, 5, 3, 2, 1 };
  for_each(a.begin(), a.end(), [](auto &item) {
      cout << item << endl;
  return 0;

The above code can only be compiled with c++14 standard. If using c++11 standard, we must use “int” instead of “auto”.

Lambda expression

Lambda expression, a.k.a anonymous function. If you are working with JavaScript, such as

var a = [ 4, 5, 3, 2, 1 ];
var found = a.find(function(item) {
    if(item == 2)
        return item;

So, the above example shows that the parameter of the find() is a function, without a function name. This is a common syntax in functional programming. Functional programming is a trend of most modern programming language. The anonymous function is also supported by PHP. The advantage of functional programming is the elimination of side effects and avoiding changing state of the data. Therefore, it is a good paradigm for parallel programming.

Therefore, looking at the example above, there is some syntax like,

  ([](int b) {
    cout << b << endl;

Which is similar to JavaScript,

(function(b) {

In C++, the squared bracket is used to capture the variable of the scope. (I think it is similar to PHP “using” keyword.)

Previously, we can use the callback function like,

#include <iostream>
using namespace std;

int foo(int (*cb)(int, void*), int size, void* data) {
  return cb(size, data);

int callback(int size, void* data) {
  int sum = 0;
  int* intData = (int*)data; //typecast
  for(int i=0;i<size;i++) {
    sum += intData[i];
    cout << intData[i] << endl;
  return sum;

int main(int argc, char** argv) {
  int a[] = { 4, 5, 3, 2, 1 };
  int sum = foo(callback, 5, a);
  cout << sum << endl;
  return 0;

Since we can use anonymous function, we need not to create a callback function like above. This can be written as,

#include <iostream>
using namespace std;

int foo(int (*cb)(int, void*), int size, void* data) {
  return cb(size, data);

int main(int argc, char** argv) {
  int a[] = { 4, 5, 3, 2, 1 };
  int result = foo([](int size, void* data) {
      int sum = 0;
      int* intData = (int*)data;
      for(int i=0;i<size;i++) {
        sum+= intData[i];
        cout << intData[i] << endl;
      return sum;
    }, 5, a);
  cout << result << endl;
  return 0;

Multi-threading, asynchronous programming, promise

We can implement multi-threading using other libraries like pthread. But with C++11, you can create thread without third party libraries, perform sleep, sleep by milliseconds or even nanoseconds. There is also library for mutex (mutually exclusive).

C++11 also supports asynchronous programming like C# and promise like JavaScript. With the lambda expression, the syntax shares some similarities with C# and JavaScript. With async, we can do something at the background (using thread), and use the result later. With promise, you can promise to return some value, else throw an exception.

Regular expression

Regular expression is so important for text processing. C++11 supports regular expression. There are different regular expression syntax: BRE (basic regular expression) is the default syntax used by “grep” command, ERE (extended regular expression, and Perl regular expression. Perl regular expression is very powerful. If you use Python, JavaScript, Ruby, and C#, you will find that they have different syntax.

However, interestingly C++ uses ECMAScript regular expression syntax by default (though we can choose BRE, ERE, or awk). That means, if you know JavaScript RegExp, then you will have no problem with C++ regex.

(I see the converging features of the different programming languages, which means these features are useful, intuitive, and influential.)


Garbage collection

So far, there is no good garbage collection for C++.


Another thing I have to state. Because of the networking and big data, parallel programming is a demand and the trend. To make sure the data is immutable, functional programming becomes handy.

Openbox + tint2

Previously I was using Xfce4. Then, because of the heavy working environment, I tried the lighter desktop environment, LXDE. But still, it has some limitations that made me choose to use Openbox window manager only.

Pros and cons of Xfce4

Xfce4 is lightweight comparing to GNOME or KDE. I like it, because of the conventional design like the task manager. Furthermore another thing I like is the “aerosnap” feature like Windows, which I can view the two windows side by side. However, when running Windows in VirtualBox and other applications, I can feel the obvious slowness in the computer. It is really reducing my working performance. That is why I decided to change to LXDE.

Pros and cons of LXDE

LXDE is lighter than Xfce4. So, running a lot of heavy applications does not slow down the computer like Xfce4. But there was one issue I faced. The LXDE pager (workspace) does not allow me to drag and drop the applications to move among the workspaces.

As a result, I decided to use something lighter than Xfce4 and I can drag and drop the applications among the workspaces easily.

Openbox and tint2

I had experienced Openbox with tint2 when I was using my old laptop. Openbox is nice and highly customisable. Tint2 allows me to set number of workspaces, and easily to move the applications to other workspaces. However, tint2 does not have applets or plugins like Xfce4 or LXDE.

There is one feature I need, that is to see CPU usage, so that I know whether there is any application causes high CPU usage. As a result, I installed Conky and display the CPU usage at the corner of the desktop.

Openbox + tint2

Openbox + tint2


For the Conky, the following is the conky.conf

conky.config = {
    alignment = 'bottom_right',
    background = false,
    border_width = 0,
    cpu_avg_samples = 2,
	default_color = 'white',
    default_outline_color = 'BBBBBB',
    default_shade_color = '444444',
    draw_borders = false,
    draw_graph_borders = false,
    draw_outline = false,
    draw_shades = false,
    use_xft = true,
    font = 'DejaVu Sans Mono:size=1', --by size 1 then only there will have no space after cpugraph
    gap_x = 0,
    gap_y = 2,
    minimum_height = 5,
	minimum_width = 5,
    net_avg_samples = 2,
    no_buffers = true,
    out_to_console = false,
    out_to_stderr = false,
    extra_newline = false,
    own_window = true,
    own_window_class = 'Conky',
    own_window_type = 'desktop',
	own_window_transparent = true,
	own_window_argb_visual = true,
	own_window_argb_value = 255,
    stippled_borders = 0,
    update_interval = 1.0,
    uppercase = false,
    use_spacer = 'none',
    show_graph_scale = false,
    show_graph_range = false,
	double_buffer = true,
	imlib_cache_size = 10,

conky.text = [[
	${cpugraph 27,40 000000 FFFFFF -l}


Cloud9 is a web-based IDE good for collaboration and online development. You can store your large project on the remote server, and use any computer including netbook with a web browser to develop your system.

Now, the problem I faced when using C9 on my Chromium. Firstly, the address bar, tabs, and bookmarks occupy some space in the window. This results a non-editor look and feel. This makes me feel lacking of something. Secondly, the worst part is the shortcut key like Ctrl+W. By pressing this shortcut key, it will invoke the web browser closing window instead of the C9 shortcut key. Meaning, the shortcut key of the web browser has higher precedence than C9 itself.

I looked for the C9 official Chrome extension, namely Cloud9, but it just works like a bookmark. I tried also Cloud 9 IDE Shortcut. It works better than official Cloud9 Chrome extension. Yet, I need to enter my username and password for the first time. Another drawback is the missing of the window icons like minimize, maximize/restore, and close, and title bar, which results difficulty to resize and maximize/restore.

Looks for some solutions. The easiest way is to invoke

chromium --app=

Yay! Now I can use the shortcut keys and it looks like native text editor!

Chromium running C9 as app

Chromium running C9 as app

If you are serious, you can write the manifest.json to create the C9 web app, then you can have a custom icon instead of Chromium icon.


Because of the new working environment, I cannot use my favourite customised Emacs to work. So, I have to adapt with the new text editor. Luckily, vim is available in the remote server. That means I can use SSH to run the vim. And, even Emacs is available, I feel difficult to customise and install the packages I need, because I don’t have experience installing Emacs’ packages using text-based UI. (But if it is available, I may make a try.)

On the other hand, vim is a little different. vim is more tend to text-based UI, though there is a GUI version called GVim. In order to familiarise with vim, I also did some customisation on it, especially the key binding (hotkey) which is, totally not user-friendly by default. So, I share my ~/.vimrc with this post.

:set tabstop=4 ai ic wrap lbr showcmd
:set shiftwidth=4
:set expandtab
:set autoread
:set list
:set listchars=eol:↵,tab:→·,space:⋅
:set whichwrap+=<,>,h,l,[,]
":set nu
:set display+=lastline
:colorscheme ron

:filetype plugin on
:syntax on

vmap <Down> gj
vmap <Up> gk

"This will be overridden by YouCompleteMe, so need to have alternave solution
imap <Down> <C-o>gj
imap <Up> <C-o>gk
imap <C-Down> <C-o>gj
imap <C-Up> <C-o>gk
nmap <Down> gj
nmap <Up> gk

nmap <S-Up> v<Up>
nmap <S-Down> v<Down>
nmap <S-Left> v<Left>
nmap <S-Right> v<Right>
nmap <S-Home> v<Home>
nmap <S-End> v<End>
imap <S-Up> <C-o>v<Up>
imap <S-Down> <C-o>v<Down>
imap <S-Left> <C-o>v<Left>
imap <S-Right> <C-o>v<Right>
imap <S-Home> <C-o>v<Home>
imap <S-End> <C-o>v<End>
vmap <S-Up> <Up>
vmap <S-Down> <Down>
vmap <S-Left> <Left>
vmap <S-Right> <Right>
vmap <S-Home> <Home>
vmap <S-End> <End>

"Remap the delete key, so that will not override the register for pasting
vmap <Delete> "_x
vmap <Backspace> "_x

"For the characters like newline (if shown with list)
highlight NonText guifg=#333333 guibg=#000000 ctermfg=darkgrey
"For special key like whitespace and tab
highlight SpecialKey guifg=#333333 guibg=#000000 ctermfg=darkgrey


GVim and Emacs

Best ever text editors: (g)vim and emacs