I want to download and install LibreOffice 4. How can I do this?
There is an official LibreOffice PPA for Ubuntu 10.10 and 10.04 (the upcoming 11.04 will have LibreOffice by default).
You need to add
ppa:libreoffice/ppa in your software sources to add it to the software center, just follow the instructions for the GUI way.
Quick and dirty CLI instructions (these will remove OpenOffice.org):
Add the PPA and install LibreOffice:
sudo add-apt-repository ppa:libreoffice/ppa sudo apt-get update sudo apt-get install libreoffice
For GNOME integration (for people running default Ubuntu):
sudo apt-get install libreoffice-gnome
or for KDE Integration (for people running Kubuntu):
sudo apt-get install libreoffice-kde
If you are using Ubuntu do not download the .deb files for manual installation, there is a PPA repository that has been available for a few weeks now. Follow these instructions to install LibreOffice from the PPA so you get automatic updates.
Keep in mind a PPA is always considered a third-party application and unfit for production purposes, however LibreOffice is becoming part of Ubuntu officially in the next release, due in April 2011, so the PPA will get a lot of attention and care. Make sure you test this and perhaps wait a few weeks if you intend to use this in 10.04 LTS or 10.10 in any significant way.
Additional language modules, help files and extensions are also available if you search for libreoffice in your package manager.
[If you get an "unmet dependencies" error, you probably need to uninstall openoffice (the installation of LibreOffice will continue automatically immediately after openoffice is purged from the system)] sudo apt-get purge "openoffice*.*"
[Also note: I got an error about Java : you may want to check that is installed before installing LibreOffice]
Starting with Ubuntu 11.04, openoffice.org packages are "transitional" packages facilitating migration from OpenOffice.org to LibreOffice. That is, they are packages that provide no actual files, but which have the corresponding LibreOffice packages as dependencies, so that LibreOffice gets automatically and smoothly installed.
Therefore, if you want to continue running OpenOffice.org instead of LibreOffice in Ubuntu 11.04 (or higher), installing Ubuntu's openoffice.org packages will not accomplish this. You will have to install OpenOffice.org from the packages provided at the official OpenOffice.org website. Before doing so, you should remove all the openoffice.org and libreoffice packages currently installed on your system, along with their global configuration files. The easiest way to do this is probably in the Synaptic Package Manager (as suggested by Uri Herrera). Mark these packages for complete removal. These packages' names are listed at https://launchpad.net/ubuntu/+source/openoffice.org and https://launchpad.net/ubuntu/+source/libreoffice (the lists overlap only partially, so check both).
Before you replace LibreOffice with OpenOffice.org, you should be aware that:
LibreOffice is currently a very close fork of OpenOffice.org. So any functional changes (including new bugs) you are seeing from the version of OpenOffice.org in Ubuntu 10.04 LTS or Ubuntu 10.10 to the version of LibreOffice in Ubuntu 11.04 are likely also to be present in the newer version of OpenOffice.org.
Once you install the upstream version of OpenOffice.org by running the installer obtained from the official OpenOffice.org website, OpenOffice.org will no longer be updated when you update the rest of your Ubuntu system in the Update Manager. Therefore, you will have to make sure it receives updates, and perhaps update it manually. It does have an automated mechanism for checking for updates, however. (I think this is in the Help menu.)