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Newbi
Asked: 2011-11-19 01:23:22 +0800 CST

Difference between commands

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What is the difference between the following?

sudo apt-get update
sudo apt-get upgrade

and

dpkg --get-selections | grep -v deinstall > ubuntu-files

plus

sudo dpkg --set-selections < ./ubuntu-files
sudo apt-get -y update
sudo apt-get -u dselect-upgrade
upgrade

1 Answers

  1. Best Answer

    The 1st part is just a normal update/upgrade.

    The last part is about saving your package list and restoring them into a new system.

    Let's say you have a crashed system and can get to a commandprompt.

    pkg --get-selections|grep -v deinstall>ubuntu-files makes a file list of all installed packages (when using apt-get!). You save that file on a FDD, USB stick or disc.

    After you installed your new system you copy that backup to /tmp/ and sudo dpkg --set-selections <./ubuntu-files will set it up and

    apt-get -y update
apt-get dselect-upgrade

    will install only those packages you had installed (with apt-get) in the older system.

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