apt-get cheatsheet

apt-get install {package}     :Install the new package. If package is installed then try to upgrade
                                 to latest version apt-get install zip apt-get install lsof samba mysql-client
apt-get remove {package}     :Remove/Delete an installed package except configuration files    
                                 apt-get remove zip
apt-get --purge remove {package}:Remove/Delete everything including configuration files    
                                  apt-get --purge remove mysql-server

apt-get upgrade, apt-get update: Resynchronize the package index files and Upgrade the Debian Linux system
                                 including security update (Internet access required)     apt-get update apt-get upgrade

apt-get update,apt-get dist-upgrade: Usually use to upgrade to Debian distribution. For example Woody to
                                     Sarge upgrade. 'dist-upgrade' in addition to performing the function
                                     of upgrade, also intelligently handles changing dependencies with new
                                     versions of packages; apt-get has a "smart" conflict resolution system,
                                     and it will attempt to upgrade the most important packages at the expense
                                     of less important ones if necessary.