====== Apt/DPKG ======
===== Cheatsheet =====
^ Taking inventory ^^
| List installed packages | ''apt list --installed'' |
| ::: | ''dpkg-query -l'' |
^ Finding files/packages                                     ^^
| Show files from installed package           | ''dpkg -L [PACKAGE]''     |
| Show installed package providing a file     | ''dpkg -S [PATHTOFILE]''  |
| Show any package that would provide a file  | ''apt-file find [FILE]''  |
| Show contents of .deb file | ''dpkg --contents [DEBFILE]'' |
^ Downgrading/Installing particular versions ^^
| Check out available versions | ''apt-cache showpkg [PACKAGE]'' |
| Install particular version | ''apt install [PACKAGE]=[VERSION]'' |
^ Marking ^^
| Mark as automatically installed | ''apt-mark auto [PACKAGE]'' |
| Mark as manually installed | ''apt-mark manual [PACKAGE]'' |
| Hold currently installed version | ''apt-mark hold [PACKAGE]'' |

===== Backports =====
  - Edit ''/etc/apt/sources.list''
  - E.g., for Debian bookworm, add <code>deb http://deb.debian.org/debian bookworm-backports main contrib non-free</code>

===== Adding "testing" repository, and getting your priorities right =====
  - Edit ''/etc/apt/sources.list''
  - Add these lines: <code>deb http://deb.debian.org/debian testing main contrib
deb http://deb.debian.org/debian unstable main contrib</code>
  - Create a new file in ''/etc/apt/apt.conf.d/'', i.e. ''80testing''
  - Insert this to make ''stable'' the default source for packages (unless you want the entire system on ''testing''): <code>APT::Default-Release "/^bookworm(|-security|-updates)$/";</code> //Take note which mainline repositories you have actually included. You wouldn't want to miss ''bookworm-security'', for example.//


===== Building packages =====