Ubuntu 16.10: Download package source code with apt source

The apt source will be failed by default. This is because deb-src is comment out in /etc/apt/sources.list.

$ apt source linux
Reading package lists... Done
E: You must put some 'source' URIs in your sources.list

Enable deb-src.

$ grep '^deb ' /etc/apt/sources.list | \
  sed 's/^deb /deb-src /g' | \
  sudo tee /etc/apt/sources.list.d/deb-src.list
$ sudo apt update  -y

The apt source will work.

$ apt source linux
Reading package lists...
NOTICE: 'linux' packaging is maintained in the 'Git' version control system at:
<snip>