看看 這一篇 有沒有幫助 debian-handbook.info/browse/stable/sect.apt-get.html
6.2.7. Tracking Automatically Installed Packages
One of the essential functionalities of apt-get (which was initially specific to aptitude) is the tracking of packages installed only through dependencies. These packages are called “ automatic ”, and often include libraries for instance.
auto
auto is used to mark a package as being automatically installed,
which will cause the package to be removed when no more manually
installed packages depend on this package.
這個指令會導致該套件的孤兒相依套件被 autoremove 移除
manual
manual is used to mark a package as being manually installed, which
will prevent the package from being automatically removed if no
other packages depend on it.
這個指令會導致該套件的孤兒相依套件不被 autoremove 移除