After a kernel update, you find the start-up menu populated with extra lines related to all the old kernel versions plus the current one. To manage the start-up manager and safely remove old kernels you have to manually operate on it.
First of all you have to double-check what is the current kernel version.
Open a Terminal and type:
uname -r
The result will be something similar to: 2.6.32-35-generic
Then you will go to the boot directory through the command:
cd /boot ls vmlinuz*
The next step will be to obtain more information about old kernel you have on our PC:
ls vmlinuz*
Now in the Terminal you have results similar to these:
vmlinuz-2.6.32-21-generic vmlinuz-2.6.32-25-generic vmlinuz-2.6.32-35-generic
vmlinuz-2.6.32-24-generic vmlinuz-2.6.32-26-generic
As last step you have to remove all the old version of the kernel using this command:
sudo apt-get remove linux-image-X.X.XX-XX-generic
where “x” is the obsolete kernel version you want to purge. In my specific case the proper command line I used was:
sudo apt-get remove linux-image-2.6.32-21-generic linux-image-2.6.32-24-generic linux-image-2.6.32-25-generic linux-image-2.6.32-26-generic
Last but not least go to System –> Administration –> StartUp Manager (available for installation on Synaptics or on Ubuntu Software Center) and select your OS choice in the Default Operating System menu. That’s all!
If you installed Ubuntu and Windows at the same time, you probably noticed that when you start your computer you can choose what operating system to launch. The responsible software for this is usually the GRUB loader and its menu. Obviously, after you install Ubuntu, it is placed as the first option and if you do not explicitly choose Windows in a few seconds, Ubuntu will be started. But what if you want Windows as your default option? Here is how you change the order:
1. Launch a new Ubuntu Terminal (Applications, Accessories). Type in the following command:
sudo cp /boot/grub/menu.lst /boot/grub/menu.lst_backup
This will create a backup of the GRUB configuration file.
2. Now open the file. We’ll do it with a new command:
sudo gedit /boot/grub/menu.lst
You will be prompted for a password, after which a text editor will be launched. In most of the situations, the menu.lst file contains many comments. You have to search for a line that says
default 0
This should not be very far from the end of file. Here you will have to intervene. After a few lines you will the variable called ‘timeout’ and its value (10 by default). If you want to have more or less time available for choosing your operating system, change the 10 with what number you want.
So back to the boot sequence. Scroll through the file again until you find:
title Ubuntu, kernel 2.6.17-10-generic
There will be more titles. Count the order number of Windows, but start from 0. The value you choose should overwrite the default one. For example, if Windows is the 4th title in the list, you will need to type
default 4
instead of ‘default 0’, which was described above. All you need to do at this point is to save the file and restart your computer.
This week, in our Linux Page (in Spanish), we have described UNetbootin: a powerful software which allows you to install many different Linux OS (Ubuntu, Fedora, openSUSE, CentOS, Debian, ArchLinux and many others) on a bootable USB key. The use of UNetbootin is really simple and after a couple of tests everyone is able to create his/her own portable OS on USB. Moreover can be used to easily install a new Linux OS directly on the local hard disk. In fact, this software properly manages Linux and Windows bootloader without causing side effects. I personally recommend UNetbootin to all the people who always desires testing the last OS versions and do not want to install them directly on their PC. Last but not least, UNetbootin is available in the followiing languages: English, Spanish, Russian, Portuguese and Hungarian. Easy, useful tool!
Today, in our Linux page we post a review about BUM a powerful, graphic Boot-up Manager for Ubuntu. Using this light software you can modify and decide what programs run at startup. BUM is a very useful tool, precious especially when you notice that your Ubuntu boot is becoming slower than in the past. Initializing the Boot-up Manager is very simple and fast: recommended for the Linux beginners (like us)!
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