How to properly manage PPAs just from the command-line

What пахал the recommendations for managing other repositories and PPAs without the help of Программное обеспечение and Updates GUI.

How to know if в repository/PPA already, - exist - enabled or - disabled?

How to handle *.list, *.list.save, *.list.save.distUpgrade поля that get filled up in /etc/apt/sources.list.d directory?

гm informed about the commands likeadd-apt-repository and ppa-purge