dup2 usage

// A simple example of how dup2 can be used
const char* msg = "Text written by standard file descriptor\n";
int fd = open("dup2_test.txt", O_RDWR | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
write(fd, msg, strlen(msg));
/* Map stdout to our file */
dup2(fd, STDOUT_FILENO);
printf("Text written by dup @ stdout file descriptor\n");

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Setting up include-what-you-need (IWYU)

Use following instructions to install IWYU (https://include-what-you-use.org/) on Ubuntu 18.04.3 LTS:

sudo apt-get update
sudo apt-get install -y build-essential cmake git zlib1g-dev libncurses5-dev llvm-6.0-dev libclang-6.0-dev libclang-6.0-dev clang-6.0
git clone https://github.com/include-what-you-use/include-what-you-use.git iwyu.git
cd iwyu.git
git checkout clang_6.0
mkdir -p build
cd build
cmake -DIWYU_LLVM_ROOT_PATH=/usr/lib/llvm-6.0 ..
make install

Once installation is complete, you will find `include-what-you-need`

# include-what-you-use --version
include-what-you-use 0.10 (git:a1878c4) based on clang version 6.0.0-1ubuntu2 (tags/RELEASE_600/final)

To execute include-what-you-need:

Build your cpp project with cmake and pass on an extra parameter -DCMAKE_EXPORT_COMPILE_COMMANDS=TRUE to cmake. It will produce  `compile_commands.json` file in your build folder for the project.

Execute iwyu_tool.py -p </path/to/folder/having/compile_command.json>. It may take time depending upon the code size.

fix_includes  can be used to apply recommended changes.

To use it in VSCode add following to the tasks.json

    "label": "Run iwyu",
    "command": "iwyu_tool.py",
    "args": [
    "presentation": {
        "echo": true,
        "reveal": "always",
        "focus": true,
        "panel": "shared",
        "showReuseMessage": true,
        "clear": false
    "problemMatcher": "$gcc"

Ref: https://gist.github.com/aakbar5/268a2072138345893b7f82590dcc3d26