James Selvakumar’s Blog

February 25, 2008

Some basic linux (ubuntu) commands for windows user

Filed under: unix-linux — James @ 3:40 pm

1. Create a directory
Windows: mkdir
Linux: mkdir

2. Remove a directory
Windows: rmdir
Linux: rmdir

3. Change to a directory
Windows: cd
Linux: cd

4. Change to a previous directory
Windows: cd..
Linux: cd ..(note one space between “cd” and “..”)

5. List content of a directory
Windows: dir
Linux: ls, dir

6. Copy file
Windows: copy
Linux: cp

7. Remove file(s)
Windows: del
Linux: rm

8. Clear the content in command shell
Windows: cls
Linux: clear

9. Display network connection details
Windows: ipconfig
Linux: ifconfig

10. Check connectivity to a machine
Windows: ping
Linux: ping

Note:
The windows os referred here is windows xp
The linux os referred here is ubuntu-7.10

Can you do this in Windows?

Filed under: ubuntu — James @ 2:21 pm

Today i happened to use the ubuntu calculator application to do some minor calculation.
I was trying to calculate the size of a file in megabytes.(which i intended to download)

This is what i wanted to calculate:
496890302/(1024*1024)

Normally, in windows, I use to do something like this:

1. Type 496890302

2. Type/press “/”

3. Type 1024

4. Type/press “/”

5. Type 1024

6. Type/press “=”

Ooohhh…

6 steps for a simple operation….!!

And how about this…?

Step 1:

Step 2: Type/press “=”

Unknowingly, I’ve been doing this many times so far in windows. What a waste of time..?

NOTE:
And one more thing..
When you take a screenshot in windows (by pressing alt+printscreen), it’s just copied to clipboard. Then you need to open an application like “Paint” or “IrfanView” to save the screenshot to a file. And the default format used by “Paint” (in my case) is “bmp”. Because of that, the size of the 4 windows calculator screenshots i posted above is about 2.9 MB.

When you take a screenshot in ubuntu (by pressing alt+printscreen), it prompts you to save the screenshot to a file. And it uses the “png” format to save the screenshots. As a result, the 2 ubuntu-calculator screenshots i posted above are about 45 KB only.

(Yes, it’s true that if I save using “png” format in windows by using some good tools like IrfanView, then i can get reduced file size. But in this post, i tried to explain the default behaviour of both operating systems)

February 24, 2008

Installing NetBeans 6.0 on Ubuntu-7.10

Filed under: netbeans,virtualization — James @ 4:40 pm

I followed the instructions mentioned in this NetBeans Wiki to install NB 6.0 on my ubuntu.

But I feel some more information can be added to this wiki.

For example, when i ran the command “sudo apt-get install sun-java6-jdk“, ubuntu complained to me that this package is not found in its repositories.

The problem here is that the package sun-java6-jdk is available in the ubuntu “multiverse” repository which is disabled by default.

In ubuntu, the repositories are defined in the file “/etc/apt/sources.list”. Take a backup of this file, in case if you want.

Now open this file and uncomment the lines which define the “universe” and “multiverse” respoitories.

It should look something like this now:

# Line commented out by installer because it failed to verify:
deb http://us.archive.ubuntu.com/ubuntu/ gutsy universe
# Line commented out by installer because it failed to verify:
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy universe
# Line commented out by installer because it failed to verify:
deb http://us.archive.ubuntu.com/ubuntu/ gutsy-updates universe
# Line commented out by installer because it failed to verify:
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy-updates universe

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
# Line commented out by installer because it failed to verify:
deb http://us.archive.ubuntu.com/ubuntu/ gutsy multiverse
# Line commented out by installer because it failed to verify:
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy multiverse
# Line commented out by installer because it failed to verify:
deb http://us.archive.ubuntu.com/ubuntu/ gutsy-updates multiverse
# Line commented out by installer because it failed to verify:
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy-updates multiverse

The job is not done yet.

Run the command “sudo apt-get update” in the terminal to instruct ubuntu to update the package details w.r.t the repositories we enabled just now.

The process might take some time. Wait patiently.

Once the update is done, ensure that the “sun-java6-jdk” package is available in the repositories, by issuing the command “apt-cache search sun-java6-jdk“. You might get something like this in the terminal window:

james@kuttima-gifty:/etc/apt$ apt-cache search sun-java6-jdk
sun-java6-bin - Sun Java(TM) Runtime Environment (JRE) 6 (architecture dependent files)
sun-java6-jdk - Sun Java(TM) Development Kit (JDK) 6
sun-java6-jre - Sun Java(TM) Runtime Environment (JRE) 6 (architecture independent files)

Now we are rest assured that our desired packages are available.

Now run the commmand “sudo apt-get install sun-java6-jdk” in the terminal. Depending on your connection speed, this might take quite some time.

Then just follow the instructions to complete the installation.

In the meanwhile, don’t forget to download the “netbeans 6.0″ installer from netbeans.org. Once you downloaded the installer, you can run it by navigating to the appropriate folder.

In my case, i needed to issue the following command:

sudo sh netbeans-6.0.1-ml-javaee-linux.sh

This will invoke the netbeans installer and just follow the instructions to complete the installation process.

That’s it, netbeans will install itself smootly on your machine.

February 23, 2008

Installing VirtualBox guest additions in OpenSuse

Filed under: unix-linux,virtualization — James @ 6:45 am
Tags: ,

I managed to install the VirtualBox guest additions for ubuntu without any problem. And as a result, I get some excellent features like “seamless mouse integration”, shared folder access etc, between my host (windows xp) and guest (ubuntu).

But when I tried to do the same for OpenSuse, I got into problem. I couldn’t run the VBoxLinuxAdditions.run from the terminal. I received an error messaage saying that “Please install GNU make, Please install GNU compiler”.

Then when I searched the web, I found this link quite useful.

As such, I executed this command in the OpenSuse terminal:

sudo zypper install gcc make automake autoconf kernel-source

It asked for my “root” password, and when i entered, it downloaded the necessary packages. (Though, i received an information that autoconf cannot be installed)

It took nearly 1 hour to download and install the necessary packages on my machine.

Then I ran the command:

sudo sh VBoxLinuxAdditions.run

after navigating to the appropriate “media” directory.

Then I was notified to restart the OS. And after that, I was able to use all the features I use with “ubuntu” as guest.

I also noticed that my OpenSuse resolution automatically increased to 1024×768 after installing the VirtualBox guest additions. (It was previously 800×600 only)

February 22, 2008

Sharing Windows XP folder with Ubuntu

Filed under: ubuntu,virtualization — James @ 4:06 pm

Since i’m new to ubuntu, all my files were basically residing in windows xp.
As i was working with ubuntu, i thought of relaxing a bit by viewing some photos taken recently. But all of them were sitting inside my xp and i need some way to access it.

Transferring them via usb is an option, but i wanted an even elegant solution. Then i came to know that VirtualBox supports “sharing” folders between “host” and “guest” operating systems.

I read in the VirtualBox manual, that “sharing” folders between “windows” host and “windows” guest is more or less seamless. But “sharing” between “windows” host and “linux” guest need some additional work.

But it’s not very tough.

First i needed to configure the shared folder in my VirtualBox. I clicked the menu “Devices->Shared Folders” to configure the sharing. And I choose a folder in my xp machine and gave a share name to that.

Then i opened the terminal in ubuntu and created a directory called share under “mnt” so it looks as “/mnt/share”. This required “admin” privileges.

Then i executed the command: sudo mount -t vboxsf myphotos /mnt/share
in the terminal. That’s it.

And this how it looked after that in the FileBrowser:

Best applications in Ubuntu-7.10

Filed under: ubuntu,unix-linux — James @ 3:40 pm
Tags:

Though there are some very good applications integrated in the default ubuntu installation, these are the one which i love most (as of now):

- GParted (Undoubtedly very very good. Extremely powerful. I use the GParted in the ubuntu livecd to resize/partition even my windows xp drives)
- Tomboy notes (Very handy, something like the “Scratchpad” in Google Desktop)
- Calculator (Really amazing, the calculator in windows xp looks very ugly to me now)

Increasing the screen resolution of Ubuntu-7.10 on VirtualBox

Filed under: ubuntu,unix-linux,virtualization — James @ 3:25 pm
Tags: , ,

Oops…finally i managed to configure my ubuntu screen resolution to the fullest.

I have a Dell Vostro 1400 laptop with Windows xp professional. Ubuntu runs on my machine on top of VirtualBox.

But I never enjoyed working with ubuntu, since all i was able to view the ubuntu desktop at the resolution “800×600″ only.

After searching through the web, I finally managed to get the full resolution supported by my notebook. (1280×800).

These are steps i followed:

- installed the virtual machine add-ons provided by VirtualBox
- opened the /etc/X11/xorg.conf file and added the the resolutions “1280×800″ and “1024×768″ under the “Screen” section…

So here is how my xorg.conf file looks now…

———————————————————————————————-
# xorg.conf (xorg X Window System server configuration file)
#
# This file was generated by dexconf, the Debian X Configuration tool, using
# values from the debconf database.
#
# Edit this file with caution, and see the xorg.conf manual page.
# (Type “man xorg.conf” at the shell prompt.)
#
# This file is automatically updated on xserver-xorg package upgrades *only*
# if it has not been modified since the last upgrade of the xserver-xorg
# package.
#
# If you have edited this file but would like it to be automatically updated
# again, run the following command:
# sudo dpkg-reconfigure -phigh xserver-xorg

Section “Files”
EndSection

Section “InputDevice”
Identifier “Generic Keyboard”
Driver “kbd”
Option “CoreKeyboard”
Option “XkbRules” “xorg”
Option “XkbModel” “pc105″
Option “XkbLayout” “us”
EndSection

Section “InputDevice”
Identifier “Configured Mouse”
Driver “vboxmouse”
Option “CorePointer”
Option “Device” “/dev/input/mice”
Option “Protocol” “ImPS/2″
Option “ZAxisMapping” “4 5″
Option “Emulate3Buttons” “true”
EndSection

Section “InputDevice”
Identifier “Synaptics Touchpad”
Driver “synaptics”
Option “Device” “/dev/psaux”
Option “Protocol” “auto-dev”
Option “HorizEdgeScroll” “0″
EndSection

Section “InputDevice”
Driver “wacom”
Identifier “stylus”
Option “Device” “/dev/input/wacom”
Option “Type” “stylus”
Option “ForceDevice” “ISDV4″ # Tablet PC ONLY
EndSection

Section “InputDevice”
Driver “wacom”
Identifier “eraser”
Option “Device” “/dev/input/wacom”
Option “Type” “eraser”
Option “ForceDevice” “ISDV4″ # Tablet PC ONLY
EndSection

Section “InputDevice”
Driver “wacom”
Identifier “cursor”
Option “Device” “/dev/input/wacom”
Option “Type” “cursor”
Option “ForceDevice” “ISDV4″ # Tablet PC ONLY
EndSection

Section “Device”
Identifier “Generic Video Card”
Driver “vboxvideo”
BusID “PCI:0:2:0″
EndSection

Section “Monitor”
Identifier “Generic Monitor”
Option “DPMS”
EndSection

Section “Screen”
Identifier “Default Screen”
Device “Generic Video Card”
Monitor “Generic Monitor”
DefaultDepth 24
SubSection “Display”
Modes “1280×800″ “1024×768″ “800×600″
EndSubSection
EndSection

Section “ServerLayout”
Identifier “Default Layout”
Screen “Default Screen”
InputDevice “Generic Keyboard”
InputDevice “Configured Mouse”

# Uncomment if you have a wacom tablet
# InputDevice “stylus” “SendCoreEvents”
# InputDevice “cursor” “SendCoreEvents”
# InputDevice “eraser” “SendCoreEvents”
InputDevice “Synaptics Touchpad”
EndSection

——————————————————————————————-
And the only change i made was here:

Section “Screen”
Identifier “Default Screen”
Device “Generic Video Card”
Monitor “Generic Monitor”
DefaultDepth 24
SubSection “Display”
Modes “1280×800″ “1024×768″ “800×600″
EndSubSection
EndSection

I just added “1280×800″ “1024×768″ under the SubSection “Display”.

Fortunately this worked for me.

(Note: I actually got this information from a VirtualBox forum thread and I sincerely thank the guy who provided this information. Thank you very much really)

Whatmore, if you choose the “Full screen mode” in VirtualBox, you get a feeling of just running ubuntu…

Ya, now i feel, i can slowly leave behind windows xp behind me…

More Ubuntu articles

Convert audio files in Ubuntu with Sound Converter

Convert video files in Ubuntu with FormatFactory

February 21, 2008

Fedora 8 added to my Linux armour

Filed under: unix-linux,virtualization — James @ 4:10 pm
Tags: , ,

First ubuntu, then open suse, now fedora….

Yes, now I have Fedora 8 installed on my machine, courtesy VirtualBox.

One interesting thing is they all have a fairly similar user interface. And all the three look very promising and very interesting.

Interesting times ahead…

(I would like to explore solaris next. If you have installed solaris on top of VirtualBox, please offer your suggestions to me)

Control System and source code quality

Filed under: java — James @ 3:06 pm
Tags: ,

Sun and other pioneers have done a great job in defining some code conventions and best practices for java development. We all know that it would be easy to maintain our java codes, if we follow these conventions and best practices.

A basic rule in Control Systems is, if you want to control some process, you need the feedback signal, so that you can regulate it.

Say, you press the accelerator in your car. You would like to know at what speed you are driving, by looking at the speedometer. Then you would like to cruise often having a look at your speedometer to control your driving speed.

So, you need some device/instrument, here in this case a speedometer, to monitor/control some process.

(Needless to say that i’m an electronics and instrumentation graduate :)

Likewise, to control the quality of your code, you need some device/instrument to give you feedback/measurement of the quality of code, so that you can take actions based on it.

It’s one thing to say to your team members, “Guys, the source code you write must follow the code conventions we have defined” and not enforcing a way to monitor it.

CheckStyle is one such tool to aid you in controlling the quality of your code. CheckStyle defines a set of “rules”, which must be followed by the source code.

The rules are very simple to use and configure. You can configure them in a xml file. An easy way to start learning CheckStyle is to have a look at the sun_checks.xml file that comes along with the downloads.

Rules are defined as “modules”. A simple rule regarding the brace position might look like this:

<module name=”LeftCurly/>

This rule checks the position of the left curly bracket “{” in your java source. The default position is “end of line”, which means:

public void myMethod() {
//do something...
}

But if your organization enforce some thing like this:

public void myMethod()
{
//do something...
}

you can configure CheckStyle to achieve that like this:

<module name=”LeftCurly”/>
<property name=”option” value=”nl”>
</module>

Or, if you want to enforce that all your methods must contain javadoc statements, it’s very easy to achieve with a simple CheckStyle rule:

<module name=”JavadocMethod”/>

To find unused, redundant imports in your java source code, just do this:

<module name=”UnusedImports”/>
<module name=”RedundantImport”/>

To make things much easy for the developers, CheckStyle offers many types of integration. You can either opt to run it from command line, integrate in your build process using ant/maven or directly integrate it with your IDE of choice.

We use both the IDE integration and the ant integration options.

If you are a NetBeans user, there are two nice plugins available:
1. CheckStyle4nb
2. CheckStyleBeans

The first one can be used to run CheckStyle rules on a java source file, package(s).
The second one integrates deeply into the IDE and marks the CheckStyle rules violations in the left side bar of NetBeans.

I use the first plugin a lot.

As the name implies, CheckStyle is more intended to check the “style”, “formatting” of your java source code, though it contains some rules to find out some “bugs” in your code as well.
But finding “bugs” and “logical mistakes” in your source code is not which CheckStyle claims to do. PMD, FindBugs might be the right candidates for that job.

But I can assure you that CheckStyle will definitely make your java source code look better and easy to maintain. Be sure to check it out, if you haven’t done so far.

February 19, 2008

OpenSuse 10.3 on VirtualBox

Filed under: unix-linux,virtualization — James @ 2:59 pm
Tags: ,

Impressed by ubuntu and being helped by VirtualBox, I decided to explore further into the linux world.

So I thought of installing openSuse 10.3 on my VirtualBox. I downloaded the gnome “live cd” (iso image) from opensuse.org. The download size was around 643 MB and it took quite some time to download the image.

Then I started VirtualBox and added a new empty virtual machine named “OpenSuse-10.3″ along with the necessary virtual hard disk. I decided to give 8 GB and 512 MB RAM for opensuse.

Then i mounted the downloaded “iso” image to the virtual machines cd drive and started the empty virtual machine. So the open suse live cd booted (much like ubuntu live cd environment) and then i clicked the “install” icon on the live cd’s desktop.

To my surprise, the installation was very very fast and amazingly simple. I would say that my opensuse installation experience was better than what I experienced with ubuntu.

Though ubuntu installation is also quite easy and smooth, opensuse installation was like installing a normal windows application. Great work.

I had to make only very few configurations to proceed with the install and the installation took less than 15 minutes.

Then i unmounted the live cd from the virtual cd drive and then restarted the virtual machine.

Wow, opensuse booted up quite beautifully and now it asked for some minor configurations like username and password.

Great. My opensuse installation was completed in notime.

And did you know what was the first activity I did after installing it? Blogged about it.

Ya. I’m writing this blog from within the opensuse running on top of my VirtualBox.

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