apt-get source on install

on apt-get install, dump corresponding source packages to /var/cache/apt-src

todo: think names, paths; package; add cleanup cmd to throw away sources for pkgs not currently installed, like apt-get autoclean

• /etc/apt/apt.conf.d/50apt-src-on-install

  DPkg::Pre-Invoke { "/usr/sbin/apt-src-on-install pre || true"; }
  DPkg::Post-Invoke { "/usr/sbin/apt-src-on-install post || true"; }
  

• /usr/sbin/apt-src-on-install

  #!/bin/sh
  
  installed() {
      dpkg-query --show \
                 --showformat='${Status} ${Version} ${Source} ${Package}\n' \
        | perl -ne '
              next unless s/^install ok installed //;
              s/(\S+) +(\S+).*/$2=$1/;
              print;' \
        | sort \
        | uniq
  }
  
  mkdir -p /var/cache/apt-src
  cd /var/cache/apt-src
  
  if test "$1" = "pre"; then
      installed > installed-pre
  elif test "$1" = "post"; then
      installed > installed-post
      diff installed-pre installed-post \
        | sed -n 's/^> //p' \
        | xargs -rt apt-get --download-only source
  fi