upgrade ubuntu 10.10 to 12.04 without using update manager

[Priti_P]

Is there any way to upgrade ubuntu 10.10 to 12.04 but without using uodate manager.
just by using any command in terminal...?

[Priti_P]

Please read it as Update manager

[JasonHippy]

It should be possible to updgrade from 10.10 to 12.04, but to be honest, it would probably be quicker and easier to do a clean install of 12.04.

Assuming you still have the update manager installed:
(Note: You will still need the update manager - if you do not have it installed, run the following command: sudo apt-get install update-manager-core)

In order to perform the upgrade via the command-line:
First back up all important documents.
Next open the file /etc/update-manager/release-upgrades with a text editor and change the line that starts with Prompt= to Prompt=normal

Note: The 'lts' setting is not appropriate here. You can only update from one LTS version to another LTS version if the currently installed version is itself an LTS version.
10.10 is not an LTS and the next LTS is 12.04. So you will have to use the 'normal' option and then you'll have to upgrade from 10.10, to 11.04, to 11.10, to 12.04.

You can do this with sudo vim /etc/update-manager/release-upgrades.
NOTE: Substitute vim with whatever your preferred text editor is.
If you use a GUI text editor (e.g. gedit or kate) you should use gksudo instead of sudo.

After saving the file and exiting your text editor, the next step is to ensure that the current install is up to date and that any unused/unneeded packages are removed:
sudo apt-get update && sudo apt-get upgrade & sudo apt-get autoremove

Finally perform the upgrade from 10.10 to 11.04 using:
sudo do-release-upgrade
This will start the upgrade process to 11.04.

Once 11.04 has successfully installed, repeat the previous two steps:
sudo apt-get update && sudo apt-get upgrade & sudo apt-get autoremove
sudo do-release-upgrade

This should upgrade you to 11.10.
Finally, repeat the two steps again to upgrade from 11.10 to 12.04.

IF all of this succeeds (emphasis on the IF part!) and 12.04 installs and is still usable:
Reopen the file /etc/update-manager/release-upgrades with your favourite editor and set the line starting with Prompt= to Prompt=lts.
That way you should be able to upgrade from 12.04 to subsequent LTS releases.

Again, it might be quicker and easier to back up all of your files, do a fresh install of 12.04 on your machine and restore your old files.