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  Something you may not know about Shell

Shell is also called command line interface, it is the interface between *nix users and computer. Shell is a program which provides service to access OS kernel services. This article is to introduce some not so well known but useful and interesting knowledge about shell. Wiki shell was born almost at the same time as Unix. The first UNIX shell was written by Ken Thompson in 1971 and its name is Thompson sh. It's older than Linux kernel. The default Shell in most *nix and MacOS is bash, bash was...

   Linux, Unix,Shell,Command     2012-11-24 07:19:47

  do {...} while (0) in macros

If you are a C programmer, you must be familiar with macros. They are powerful and can help you ease your work if used correctly. However, if you don't define macros carefully, they may bite you and drive you crazy. In many C programs, you may see a special macro definition which may seem not so straightforward. Here is one example: #define __set_task_state(tsk, state_value) \ do { (tsk)->state = (state_value); } while (0) There are many this kind of macros which uses do{...}while(0)...

   C,macro,C++     2014-01-23 07:16:13

  Replacing small C programs with Haskell

C is the classic go-to tool for small programs that need to be really fast. When scripts.mit.edu needed a small program to be a glorified cat that also added useful HTTP headers to the beginning of its output, there was no question about it: it would be written in C, and it would be fast; the speed of our static content serving depended on it! (The grotty technical details: our webserver is based off of a networked filesystem, and we wanted to avoid giving Apache too many credentials in ca...

   C,Haskell,Small program     2012-01-03 10:51:39

  Microsoft forms a new subsidiary focused on open source called Microsoft Open Technologies

Microsoft once again changes its attitude and intends to set up an open technology subsidiaries in order to promote the formulation of open-source projects and standards.The new company name is Microsoft Open Technologies and Jean Paoli, Microsoft executives will be the president of the new company. The company will also form interoperability strategy team in the future. The newly established company will have about 50-75 employees.Over the years, Microsoft has been considered to be the rival of...

   Microsft,Open source,Microsoft Open Technologies     2012-04-13 06:10:45

  Gracefully exiting from console programs in Ruby

Imagine you write a CLI program or a Rake task which loops through some data performing some work on it. You run it and then you remembered something. You’d love to kill the process with ctrl-c, but that will raise an exception somewhere in the loop. What you want is for the iteration to complete and then you want the program to quit. You could handle the Interrupt exception or add some conditions. But how about a cleaner and reusable way? No problem - you can trap signals, which...

   Ruby,Exit,Command window,Console,Graceful     2012-03-14 13:42:16

  Mount DD image on Linux

Yesterday, my Raspberry Pi running Arch Linux was not able to boot with error: Kernel Panic, not syncing: no init found. I spent a night on it, but could not find a working solution. The last option is easy: reinstall the system. That is really the last resort, for I do not want to re-setup everything I have done: samba server, Time Machine server, Xunlei Offline Downloader… Unable to mount the SD card The system does not boot, so I need to find a way to get into the file system to identi...

   LINUX,DD IMAGE     2014-06-24 07:49:14

  Go vs C benchmark. Could Go be faster than C?

During last semester I was attending Multiprocessor Architectures course, given at Facultad de Informática where I study my Computer Science degree. As part of the assignments due to pass the course, we had to do several programs written in C to benchmark matrix multiplication by testing different techniques and technologies. First of all we had to do a secuential program in three different versions: A normal one where the result matrix is ordered by rows and the loops range the matrix by ...

   Gp,C,Benchmark,Faster,Speed,Comparison     2012-02-08 10:09:07

  6 amazing HTML5 animation effects

HTML5 is rapidly developed in WEB world, it puts all kinds of pressure to browser development, but at the same time it also brings us lots of unexpected page effects. If we can use some HTML5 elements on our web apps,  we may get different user experience. However, for HTML5, there are lots of places need to improved. The following HTML5 animation effects are very attractive. 1. HTML5 mouseover image effect This HTML5 animation effect can be used in photo gallery, users can preview the...

   HTML5,Animation     2012-11-20 10:32:52

  Simple explanation about process and thread

Process and thread are two basic concepts of operating system, but they are a bit abstract which cannot be  mastered easily. There is an analogy which explains these concepts very well. 1. The kernel of the computer is CPU, it handles all the computing tasks, it's like a factory and will run all the time. 2. Assume there is power limitation for the factory, it can only supply to one unit once,i.e, when one unit is working, other units must stop and wait. The meaning behind this is that eac...

   Process,Thread,CPU,Operating system     2013-04-24 11:33:10

  bash network interface

Some of us may have seen /dev/tcp/<host>/<port> before, is this a special file system implemented in some BSD kernel? Because there is no /dev/tcp in Linux. Actually, this one is implemented in bash. We no need to rely on wget,nc to do network connection. It's very easy to use this interface: bash-4.2$ cat </dev/tcp/time.nist.gov/13 56188 12-09-18 15:34:26 50 0 0 733.5 UTC(NIST) * bash-4.2$ exec 3<>/dev/tcp/www.w3.org/80 bash-4.2$ echo -e "GET / HTTP/1.0\n\n" >&3 b...

   Bash,Network interface,/dev/tcp     2013-07-20 00:57:52

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