Sometimes we refer to a file or a command and you might wonder, in which package it will be found. Fortunately the Debian repositories not only contain information about all the binary packages provided, but also all the files shipped with them. This information is stored in files named Contents-arch.gz and Contents-udeb-arch.gz. This information is not automatically downloaded by APT after installation. Instead it needs the apt-file update command (from the similar named package) to initially retrieve the contents of all package sources mentioned in /etc/apt/sources.list. By default it downloads Contents*.pdiff files as described in sidebar TIPP Inkrementelle Aktualisierungen to reduce the amount of data necessary to be downloaded. To update the database on a weekly base, the following entry can be added to /etc/crontab if convenient. After installing apt-file, every apt-get update will also retrieve and update the Contents files.

@weekly root test -x /usr/bin/apt-file && /usr/bin/apt-file update >> /dev/null 2>&1

Nachdem die Datenbank aktualisiert wurde, listet der Befehl apt-file search Muster alle Pakete auf, die einen Dateinamen oder Pfad enthalten, der dem Muster entspricht.

$ apt-file search bin/axi-cache
apt-xapian-index: /usr/bin/axi-cache

Der Befehl apt-file list Paket listet stattdessen alle Dateien auf, die mit dem Paket ausgeliefert wurden.