1. # the following command produces (given two source trees ~/original/sources and ~/updated/sources) an overview of the differences between these two trees:
     cd ~/original/sources
     tar -xzvf ~/whatever.tgz
     cd ~
     diff -ruN original/sources updated/sources > how.to.patch.original.sources
  2. # the following command produces, given the original source tree and the differences between the original and updated sources, updated sources:
     cd ~/current/sources
     tar -xzvf ~/whatever.tgz
     patch -p2 < how.to.patch.original.sources