A developer needs to fetch the upstream source of a package with apt-get source, but the command reports that it must find a source package line. Which kind of entry has to be added to /etc/apt/sources.list?

LPIC-1 Exam 101-500, objective 102. Linux installation and package management medium

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The options

Correct A line beginning with deb-src, otherwise identical in URI, suite and components to the binary line.

Correct. deb-src entries point APT at the source package indexes; binary and source repositories are listed separately even when they share a URI.

Not correct A second deb line with the component source added after main.

Wrong. source is not a component like main, contrib or non-free; the archive type is what changes, at the start of the line.

Not correct A line beginning with src-deb followed by the mirror URI.

Wrong. There is no src-deb keyword; the only archive types in this file are deb and deb-src.

Not correct A line setting APT::Get::Source in /etc/apt/sources.list.

Wrong. sources.list holds repository entries only; APT configuration options belong in /etc/apt/apt.conf or /etc/apt/apt.conf.d.

Why

Each one-line entry in /etc/apt/sources.list has the shape: archive type, URI, suite, then one or more components, as in deb http://deb.debian.org/debian bookworm main contrib. The archive type deb selects binary packages and deb-src the corresponding sources, so fetching sources needs its own line and its own apt-get update. Additional repositories are usually added as separate files under /etc/apt/sources.list.d instead of editing the main file.

Where this comes from

Cited
manual page sources.list(5)

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Practise LPIC-1 Exam 101-500

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