How can I upgrade Ubuntu to the latest version Ubuntu 14?

1. Back up important data on the Ubuntu Server
Back up data. Most of the operations in this article must be performed by root, which may cause irreparable losses.
Enter the following command to view the existing system version:

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$ Uname-mrs $ Lsb_release- The output is as follows: Linux 3.2.0-51-generic x86_64 No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 12.04.4 LTS Release: 12.04 Codename: precise

2. How can I upgrade from the old Ubuntu 13.10 version to the new 14.04 version in the server system?
Run the following command to upgrade the old software package of the system and install the update-manager-core package (if your system has not installed update-manager-core ):

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$ Sudo apt-get update $ Sudo apt-get install update-manager-core

Then enter the following command? Upgrade the Ubuntu Server to the latest version, such as 14.04 TLS. We recommend that you use the following commands in environments where the graphic interface environment is not installed or the server is upgraded remotely using ssh. :

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$ Sudo do-release-upgrate

Do-release-upgrate will run the upgrade tool. You only need to follow the prompts on the screen.
3. Repair and force upgrade
You may eventually get the following information on the screen when you run do-release-upgrate:
Checking for a new Ubuntu release
No new release found
Warning: The following method will check if upgrading to the latest devel (also known as unstable) release is possible via-d option.
To force the upgrade, you can add the-d parameter as follows:

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Sudo do-release-upgrade-d

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Reminder: how to upgrade the system from the desktop of Ubuntu 13.10
First, you need to remove all third-party binary drivers, such as NVIDIA or AMD graphics card drivers. Once removed, restart the desktop. Press ALT + F2 and enter update-manager in the command box.
Update manager will open and tell you: New distribution release '14. 04 LTS 'is available (the new version 14.04 LTS is available ). click Upgrade and follow the instructions on the screen.
Note that all TLS desktop users need to wait until an instance named Ubuntu LTS v14.04.1 is released. If you do not want to wait for this version, you can use the-d parameter in update-manager to upgrade. You can upgrade Ubuntu 12.04 LTSs to Ubuntu 14.04 LTS in this way:
Sudo update-manager-d
 
4. Restart the server/desktop
Finally, restart the system.

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$ Sudo reboot

Then confirm whether you have upgraded to the latest version;

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$ Lsb_release- $ Uname-mrs $ Tail-f/var/log/app/log/file

Confirm the upgrade to the latest version, and then reinstall the third-party binary driver.