Fixing Virtual Box after kernal update

After kernal update the following error displayed in virtual box:

Result Code: NS_ERROR_FAILURE (0x80004005)
Component: Machine
Interface: IMachine {13420cbb-175a-4456-85d0-301126dfdec7}

Just use following command to fix the same

sudo /etc/init.d/vboxdrv setup

it will recompile virtualbox

Change machine name in ubuntu

To change machine name in ubuntu use following command:

sudo gedit /etc/hosts /etc/hostname

for Xubuntu use command

sudo nanao /etc/hosts /etc/hostname

It will open two files in different tabs of geditor. Change hostname in both the files and save. Quit the geditor / nano

The machine name has been changed, re-login to see the change.

Using no-proxy setting in firefox

as in internet explorer and opera browsers we can add ip ranges (in format 192.168.* for ip range 192.168.0.0 to 192.168.255.255) for which no proxy should be used, but firefox handles this setting differently, it does not accepts wild cards *. for the same range 192.168.0.0 to 192.168.255.255 setting in firefox should be:
Goto>> Edit >> prefernces (Tools >> options) for windows)

Goto > Advanced >> Network

in Settings use manual proxy settings
in no proxy for settings there should be localhost, 127.0.0.1
for adding above mentioned ip range add 192.168.0.0/16 and it should look like
localhost, 127.0.0.1, 192.168.0.0/16

192.168.0.0/16 means, starting from 192.168.0.0 to 2^16 ipaddress

(2^8 = 256 & 2^16 = 256x256)

Using remote desktop connection on ubuntu

Remote desktop: for accessing windows machine's desktop from ubuntu, use following command:

rdesktop 192.168.1.2

where 192.168.1.2 is the ip address of remote machine (windows). 

More options:

rdesktop 192.168.1.2 -f -u xyzabc

will open dektop of 192.168.1.2 in full screen with username "xyzabc", we have to enter password in login window (username has alredy been given)

Adding Windows like icons on Ubuntu desktop

For adding windows like icons on ubuntu desktop run following command from terminal:

gconf-editor

go to apps>> nautilus>> desktop

check the boxes against icons (for desktop icons you want) like
computer_icon_visible
documents_icon_visible
network_icon_visible
trash_icon_visible

Formatting pen drive in ubuntu

Gparted is the software for formatting USB pen drive in ubuntu with simple graphical user interface. It can be installed from ubuntu repositories by Synaptic Package Manager.

Alternatively, it can be installed by giving command in terminal:

sudo apt-get install gparted

Insert USB drive, right click on it and select unmount. Now open gparted by giving command in terminal:

sudo gparted

select the pen drive carefully from gparted>>devices
it will show like:
/dev/sda (149.05GiB)
/dev/sdb (249.79MiB)

as in my case for 256MB pen drive it is showing /dev/sdb (249.79MiB)

after selecting click on Partition>>format to>>fat32

click on Apply to Format.