Apt-get/dpkg

• apt-get

  apt-get install package 

  install package

  apt-get update  

  update sources

  apt-get upgrade 

  upgrade all upgradeable packages

  apt-get remove package 

  remove package

• apt-cache

  apt-cache search regexp 

  search packages names and descriptions for regexp

  apt-cache show package 

  show package info

• apt-file

  apt-file update 

  update file contents lists

  apt-file search regexp 

  search package contents for file name containing regexp

• dpkg

  dpkg -s package 

  show status of package

  dpkg -L package 

  list files in package

  dpkg --get-selections 

  list all installed packages