Retrieve list of installed packages, Save a list of all programs installed on Ubuntu

Next week I will make an installation of Ubuntu 11.04 beta 2 (64 bits) from scratch, but I will not lose the programs that I have currently installed. I searched on the solution to this problem is that with a single command can save a list of all packages installed on our current Ubuntu installation. The procedure is as follows:

First keep the list:

dpkg --get-selections | grep -v deinstall > ubuntu-files #this can be changed by the name you want, it will save the file where the list but should be no spaces

One problem you may encounter is that you do not have the same list of repositories. To fix that use this command (before formatting):

cp /etc/apt/sources.list ~/sources.list

Now save the files in a pen or on a hard drive that we will not format, which will be in our home folder.

For when you want to install it, the first thing to do is join the two lists of repositories, copy only the deb or deb-src of the old equipment, not to fill it with unnecessary comments the new repositories.

And when you want to install use these commands:

sudo apt-get update
sudo apt-get dist-upgrade
sudo dpkg --set-selections < ubuntu-files
sudo dselect install

If you appear as non-existent dselect is that you must install:

sudo apt-get install dselect

This is can be used both for domestic use, as I do, or to install the same software on multiple computers, such as a company.