直接取自apt-get的手冊頁:
update
update is used to resynchronize the package index files from their
sources. The indexes of available packages are fetched from the
location(s) specified in /etc/apt/sources.list. For example, when
using a Debian archive, this command retrieves and scans the
Packages.gz files, so that information about new and updated
packages is available. An update should always be performed before
an upgrade or dist-upgrade. Please be aware that the overall
progress meter will be incorrect as the size of the package files
cannot be known in advance.
upgrade
upgrade is used to install the newest versions of all packages
currently installed on the system from the sources enumerated in
/etc/apt/sources.list. Packages currently installed with new
versions available are retrieved and upgraded; under no
circumstances are currently installed packages removed, or packages
not already installed retrieved and installed. New versions of
currently installed packages that cannot be upgraded without
changing the install status of another package will be left at
their current version. An update must be performed first so that
apt-get knows that new versions of packages are available.
更新來更新apt-get的軟件包列表,升級來安裝更新爲全部爲包。要僅更新一個包,請使用install。
sudo apt-get install firefox
約翰你好,你的問題不是一個編程問題。在StackExchange中嘗試超級用戶。 – drum 2012-07-15 19:23:06
不是一個編程問題,所以脫離堆棧溢出的話題。 [askubuntu.com](http://askubuntu.com)將是一個更好的地方來問這個問題。 – Oded 2012-07-15 19:23:27