The best virtualization software: VirtualBox v/s VMPlayer

I was an avid user of VirtualBox and was pretty happy with it. It gave me freedom to experiment with different OS in a rather safe, transparent, and convenient way. So I used to keep Linux as host and Windows as guest. Performance was good and bugs were non-existent.

Then I found VMPlayer. It surprised me a lot with following reasons:

a) It supported ISO images for Ubuntu, my fav Linux disto.

b) Set up was easier/comparable to VirtualBox.

c) Unity mode: What a feature! A seemless integration of guest OS with host application. You don't have to click the mouse, you never lose window focus. I can now browse through guest OS with Alt+Tab.

d) Very stable, good performance, and I am a happy customer.

How tail -f work?

"tail -f" is a special command in a way that it polls the specified file for any change and prints the new stuff on the fly. It is very helpful in observing logs and any event based data.

Ever wondered how tail achieves this?

"tail" opens the given file and obtains the file-descriptor. It opens it with xfreopen() -> freopen() -> fopen() call. It does its first round of fstat() on the file as well.

Once it has got the fd, it loops infinitely and do the following:

It does fstat() of the file and observes the mtime value. If the mtime value is changes from the last time..it dumps the data. To print the latest data, it lseek() the file to the last reported file size.

Source: http://git.savannah.gnu.org/cgit/coreutils.git/tree/src/tail.c

How touchpad of a laptop work?

It was a curiosity to know the internal details of one of the most used 6x6 cm2 part of a laptop. My curiosity increased with diffrent behavior of the touchpad with different objects. For example, it works well with fingers but a pen, pin, or paper are not entertained.

So how does it work?

It is based on concept of capacitive difference on two parallel plates. Each of these plates have a grid of conductors. When we put our finger on the surface, it creates a charge difference on this surface and the difference of capacitance is sensed by the hardware.

This difference is mapped to mouse motion on our screen.

MeeGo: Marriage of Nokia and Intel

Nokia and Intel are merging their Linux based intiatives: Meamo and Moblin = Meego

* Open source platform to serve mobiles, notebook, TV, and tablets.
* Hosted under Linux Foundation
* Support x86 and ARM
* Visit http://meego.com for more information

But why would people use this new OS? What's wrong with Andriod? How is it better than Symbion, Android, Windows Mobile or BADA?

We already have Linux based mobile OS, so it'd be hard for this new guy to find a decent place.

Uninterrupted Linux session : screen command

Have you ever faced losing connections to a remote machine(e.g. from a putty) and you happened to be in middle of a script that took ten hours to complete. So what would you do??

Restart the script after re-connecting.

Not anymore...

Linux screen solves this problem with providing a terminal that runs on server and just exported to your putty/Terminal client. In simple terms, you are running your putty on remote machine and watching the output on your local client.

Now, if you client goes down, just chill!

Screen is running your script on remote machine.

To start a screen session:
- Login to remote machine with as you may wish.
- Run $screen
- Do you stuff

Power cut and, no net connection and your client is down.

Once power is back, just re-login to remote machine.
and issue:
$screen -r

It'll list all screen sessions running on the remote machine. Get attached to one of the session with:

$session -r

Now,