Links I follow



  • All about Void, void variable and void function
  • How to read a function in C .
  • strncpy Synopsis:#includechar *strncpy (char *dest, char *src, int n); Description:The strcpy function copies n characters from src to dest up to and including the terminating null character if length of src is less than n.
  •  Invalid use of void expression.
  • Good for understanding C
  • Main arguments and their counts [1]
  • C tricks [1]
  • Macros in C [1]
  • IPC Shared Memory [1] [2] [3] [4]
  • Passing Pointers using SHM [1]
  • Malloc [1]
  • malloc function allocates a specified number of bytes of memory. The initial value of the memory is indeterminate.
  • calloc funtion allocates space for a specified number of objects of a specified size. The space is initialized to all 0 bits.
  •  realloc function increases or decreases the size of a previously allocated area. When the size increases, it may involve moving the previously allocated area somewhere else, to provide the additional room at the end. Also, when the size increases, the initial value of the space between the old contents and the end of the new area is indeterminate.
  • Function Pointer [1], [2], [3], [4]
  • String Concatenation Best way [1]

Signal in C:





  • Java Interview Question [1] [2]
  • Difference between Throw and Throws [1], [2]
  • Exception handling ORACLE
  • Struts Tutorial [1]


  • The suffix tree for S is actually the compressed trie for the nonempty suffixes of the string S. Since a suffix tree is a compressed trie, we sometimes refer to the tree as a trie and to its subtrees as subtries.
  • Trie Data structure  [1] can help to create the Suffix Tree.
  • Quora
  • StackOver Flow  [1]

Tic-Tac-Toe :

Data Structure

  • Basic data structure [1] [2]




  1. best link to read about Xenomai with examples. [2] [3]
  2. Same link as above but with extra Explanation.
  5. Automatic Code generation for Xenomai [1]
  6. Printing in Xenomai [1],[2]
  7. Xenomai Timer :Xenomai has two time sources: the sytem timer, which counts the number of nanoseconds since 1970, and a hardware dependent high resolution counter which counts the time since an unspecified point in time (usually the system boot time). This hardware dependent high resolution counter is called “tsc” on a PC, and gave its name to Xenomai native API calls.rt_timer_tsc returns the value of this hardware dependent high-resolution counter.
    rt_timer_info returns the same thing in the tsc member of the RT_TIMER_INFO structure, and the value of the system timer at exactly the same time as when the high-resolution counter was read.This allows to have a correspondence between the two time sources.rt_alarm_inquire is not related to this and returns some information
    about a given alarm. Now, if you allow me, a little advice for the implementation of a “timer library”: you could be tempted to create only one periodic alarm object with Xenomai, and to manage a timer list yourself. Don’t do this. Creating an alarm object for each timer library object make Xenomai aware of the existence of all your application timers, this has severaladvantages:
    – it gives you information about all your timers in /proc/xenomai
    – it allows Xenomai to use its anticipation algorithm for all your timers
    – if you are concerned about the scalability of Xenomai timers list
    management, you can check the options in the “Scalability” menu of
    Xenomai configuration menu (“Real-time subsystem” sub-menu of kernel
    configuration menu).
    more about timersXenomai POSIX skin supports two clocks:
    CLOCK_REALTIME maps to the nucleus system clock, keeping time as the amount of time since the Epoch, with a resolution of one system clock tick.CLOCK_MONOTONIC maps to an architecture-dependent high resolution counter, so is suitable for measuring short time intervals. However, when used for sleeping (with clock_nanosleep()), the CLOCK_MONOTONIC clock has a resolution of one system clock tick, like the CLOCK_REALTIME clock.[1]

Xenomai Semaphore Example Codes :

Process Scheduling :

  1. Priority Inversion :

2. Priority inheritance :


syslogd from BusyBox

  • Syslogd from  busy box have problem like it can’t Log to two different files. Explained here  [1]

Communication Protocols For Automation Profibus

  • [1]  All about ProfiBus

Compiler and Linker


Device Mapper Busy Error [1]


  • How to remove a commit from branch [1]
  • To recover all unstaged deletions at once, automatically, without specifying each single path:
    git ls-files -d | xargs git checkout --

    To recover all staged deletions at once, automatically, without specifying each single path:

    git status | grep 'deleted:' | awk '{print $2}' | xargs git checkout --


    • Learn Docker form the Basics [1]
    • Docker is like virtual environment better for development.[1] [2]
    • Egg(Docker) and Chicken(Ubuntu) problem of course, Here chicken came first [1] . Interesting things about Docker !!
    •  You need a 64bit OS in order to use Docker. (Remember This)
    • Copy file from container to host 
    • Docker cheat sheet with examples 
    • Removing a Image from docker — [1]
      docker rmi the_image
    • Removing all images from docker
      docker rmi $(docker images -q)
    • Removing all images except some of them you wanna retain
docker rmi $(docker images | awk '$1!~/ubuntu|free_dcs_development_env_v1.0/ && NR>1 {print $3}')
  • Removing all containers not image : To remove all existing containers (not images!) run [1]
    docker rm $(docker ps -a -q)
  • Volumes and File sharing by Red-Hat
  • Boot2Docker Way to share folders between Host to container [1] :Is it possible that you use docker on OS X via boot2docker or something similar. I’ve made the same experience – the command is correct but nothing (sensible) is mounted in the container, anyway.As it turns out – it’s already explained in the docker documentation. When you type docker run -v /var/logs/on/host:/var/logs/in/container ... then /var/logs/on/host is actually mapped from the boot2docker VM-image, not your Mac.You’ll have to pipe the shared folder through your VM to your actual host (the Mac in my case).
  • Mounting a host’s folder to container finally Done :
docker run --privileged  -it -v /home/arun/freedcs:/home/arun/freedcs free_dcs_development_env_v1.0:latest /bin/bash

Windows 7 Cracking

  • Using Ophcrack.iso Burn this to your device(Flash or CD rom) and Please read this link

IOS X 10.9


Technical Websites :

Non Technical

Maths(Which i don’t like at all)

Puzzles & Algorithms


  1. Zen habits. I love this website.