How to Remove Kerberos Password in Linux

This is a very rare situation one might face. Suddenly your linux based computer, VPS or server might prompt you to enter Kerberos Password. Same thing happened to me, I don’t remember if I had set kerberos password in the past. I had only updated certain packages. This happened when I tried assign new password to an existing vsftpd user. In this case all I could think of is getting rid of Kerberos password to proceed with my work.

Kerberos password is network authentication protocol which allow nodes communicating over a non-secure network to prove their identity to one another securely. Now to get rid of Kerberos password, all we need to do is removing a package that causes the issue. However this is a security feature that one might use if they are conscious about their data.

To remove Kerberos Password in Linux:

sudo apt-get remove –purge libpam-krb5

This will now remove the kerberos password.

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How to Compile and Install a Tar file in Linux

The .tar file format is derived from the phrase “tape archive”. Developers often use this format to compress and distribute their sources. By doing this, they need not worry about the platform, so anyone on any platform can directly compile and install on their computers. This short guide will teach you how to extract an tar file, compile and then install it on any linux distro.

After you download a .tar file, open Terminal and navigate to the directory where the file exists using ‘cd’ command. Then perform following commands:

xvzf packagename.tar.gz
cd packagename
./configure
make
make install

That’s it. The program should be installed now.

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How to Install MATE desktop environment in Ubuntu 12.04

MATE is a fork for GNOME which makes it a purely traditional much loved environment that we had in GNOME 2. This simple guide lets you install MATE on Ubuntu 12.04 with ease by following the simple procedures below:

Add the repository to the source list:

sudo add-apt-repository “deb http://packages.mate-desktop.org/repo/ubuntu oneiric main”

Then:

sudo apt-get update
sudo apt-get install mate-archive-keyring
sudo apt-get update
sudo apt-get install mate-core
sudo apt-get install mate-desktop-environment

That’s it. You should now be able to select MATE from the login screen.

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File Permissions in Ubuntu

Ability to set file permissions for individual users or user-groups is one of the most sought after features of Linux. If you are system admin for a school, college or a company you work for then proper file permission setting is among the most vital tasks.

The command used to modify file permissions is chmod, short for change mode of a file. You can also use Nautilus file browser to change the file permissions. I will cover the details after a little background on the file permissions. To find the permission settings for a file, issue the following command int he terminal from the directory where your file is.

ls -l
cmd output

As you can see, the first column in the output has some strange looking character sets. This set is the file permissions for that file (directory). The third column is the owner of the file (directory) and the fourth column is the default group of the file (directory). We can ignore all the other columns at this point.

In the first column, each set would be 10 character wide. The very first character is a d for a directory or just a (hyphen) for files. After that, the next three characters are the permissions for the owners account. The order is read-write-execute. If the superuser can read the file it would display r otherwise just a . Similarly for write and execute w and x would be displayed. The next three characters are permissions for all the other users belonging to the file group (from the fourth column in the output above). Final three characters are the permissions for everyone not part of the group. Superusers (root accounts) can always override all the settings mentioned here and none of the permissions apply to them.

Changing Permissions – The Easy Way

The easiest way, as I said, is to just change the file permissions using Nautilus but it’s time consuming if you want to change the permissions of a lot of files. Command line way may seem tedious to begin with but it’s the faster way once you know your way around. To change the permissions in Nautilus, right click on any file (directory). Go to properties and then to permissions. Change the permissions and click ok. That’s it.

File Permissions

Changing Permissions – The Faster Way

To change file permissions via the terminal, you can use the chmod command. To change permissions of a file, enter the following command in the terminal.

chmod ABC path/to/file

Here, ABC is a 3 digit number which is the decimal representation of the file permissions. For example, r-x means 101 in binary which translates to 5 in decimal. So, if you want everyone to have just read and execute access to files and only the owner has the write access to files then the permissions are rwx,r-x,r-x which is 111,101,101. That translates to 7,5,5 (comma is only given for clarity here). So, the command would now be,

chmod 755 path/to/file

Don’t worry if you don’t know how binary works, you will get used to it. Easiest way is add 4 for read, 2 for write and 1 for execute. So, considering the examples above, rwx = 4 + 2 + 1 = 7 and r-x = 4 + 0 + 1 = 5. You’ll get used to this. There is another way to to this, the text method (which I don’t prefer).

chmod who=permissions filename

Where Who is any from a range of letters, and each signifies who you are going to give the permission to. They are as follows:

u – The user that own the file.
g – The group the file belongs to.
o – The other users i.e. everyone else.
a – all of the above – use this instead of having to type ugo.

And then you can directly write rwx in front of the equal sign. For example,

chmod g=rx

Next post will cover setting default permissions to files you create using umasks.

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Install Nvidia 275.21 on Ubuntu 11.04 and 11.10

Nvidia 275.21 has been released. This version adds support for GeForce 540M and fixes a some of the problems. Following are some of the features:

Note: This driver will only works for Geforce 6 series and above

Restored the release splash screen in the NVIDIA X driver (the beta splash screen was accidentally reenabled between 275.09.07 and 275.19).
Fixed a bug that caused nvidia-settings to crash when configuring multiple X screens after all monitors were unplugged from one of the X screens.
Fixed a bug in nvidia-settings that caused the display configuration page to show extra disabled displays after connecting a new monitor.
Added X configuration options “3DVisionProHwButtonPairing”, “3DVisionProHwSinglePairingTimeout”, “3DVisionProHwMultiPairingTimeout”, and “3DVisionProHwDoubleClickThreshold” to configure hardware button based pairing in NVIDIA 3D Vision Pro. See “Appendix B. X Config Options” in the README for more information.
Fixed a bug that prevented initialization of the NVIDIA 3D Vision or NVIDIA 3D Vision Pro hub if no EDID was present.

How to install Nvidia 275.21 on Ubuntu 11.04 and Ubuntu 11.10 using PPA

sudo add-apt-repository ppa:ubuntu-x-swat/x-updates
sudo apt-get update
sudo apt-get install nvidia-current

All you have to do is to enable the drivers by going to

System–>Administration–>Additional Drivers

and activate the driver

All that is left is to reboot the machine to see the drivers in action

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Install Firefox 8 nightly on Ubuntu 10.04, 10.10, 11.04, and 11.10

This is a quick post on adding the nightly PPA of Firefox for Ubuntu 11.10. The current version of this nightly build is Firefox 8. Firefox has been loosing constant market share to mainly Google’s Chrome. The result being some quick updates are now being rolled out to Firefox.

Note: This is a nightly build and will have some bugs so please use it at your own risk.

sudo add-apt-repository ppa:ubuntu-mozilla-daily/ppa
sudo apt-get update
sudo apt-get install firefox-trunk

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Change the Keyboard Layout in Fedora 15 {LoveLock}

Fedroa 15 was released a while back and as much as it has shown some tremendous improvements, I fail to understand why should it be rocket science to do something as simple as changing the keyboard layout. With Gnome 3 making Fedora 15 shine, it should be easier to just type “keyboard layout” in the search box to come to the screen for changing the layout of keyboard. However that is not the case. So in order to change the keyboard layout (different language keyboard layout) follow the steps below:

Note: The keyboard setting under Activities > Applications > System Settings > Keyboard doesnt have the option to change the keyboard layout.

Go to:

Activities > Applications > System Settings >  Region and language and click the Layout tab.

Click the + buttonto add a keyboard layout.

Play around with rest of the settings.

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Unity Opera

Kyle Baker of Kyleabaker.com has written a lovely script to unite Opera with the new Unity interface of Ubuntu 11.04. Unity Opera has the following features:

Count:

Total number of tabs open appears on the launcher Icon and is updated in real time as you open or close the tabs.

Note: The private tab counts is not shown

For complete list of features, download and instructions to install checkout the post by Kyle Baker at Unity Opera.

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Install Chromium Dev version in Ubuntu 11.04

When you install Chromium on Ubuntu 11.04 using the software center you get the stable version on your machine. However, if you want to flirt around with the latest features you will need the Dev channels to be able to use the developer version of Chromium. Let's see how to update the channels to dev version to install the latest developer version of Ubuntu 11.04.

Adding the dev channels repository to your Ubuntu Repos:

[sourcecode lang='bash']
sudo apt-add-repository ppa:chromium-daily/dev
sudo apt-get update
[/sourcecode]

Once you have added you can start your update manager to update chromium (currently 12).

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How to change the Hostname in Ubuntu

There are times you may come up with a need for change in your computer’s identity over network. This is when you will have to change the Hostname of your computer. The hostname is pretty much like a label to your computer or the device for identification over the network. The hostname can be just a simple name, an IP Address or even a domain name.

To change the hostname in Ubuntu, follow these simple steps:

1. Find out your existing hostname by entering this command in terminal:

hostname

hostname ubuntu

So on my computer, the hostname is “santhosh-desktop”

2. Change the hostname by editing:

sudo nano /etc/hostname

You will see the existing hostname. Change it to whatever new hostname you want and save it by hitting Ctrl + O

In this tutorial, I change it to

gigacore-desktop

3. Now edit the hosts:

sudo nano /etc/hosts

Here change the ::1 and 127.0.1.1 to the new hostname you chose.

::1 gigacore-desktop localhost6.localdomain6 localhost6
127.0.1.1 gigacore-desktop

3. Restart the hostname service.

sudo /etc/init.d/hostname restart

Now check the hostname by following the step 1 and you should see the new hostname.

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