Configuration within first lines of script

  pattern="Flurst"

  regin="Flurst.ck \(.*\) Gemarkung \(.*\)"
  regout="\1_\2.pdf"

  mod="s/[\/, ]/_/g"

Usage and output

  ./adaptive_river test.pdf 

  1 -> 123_Oberhausen.pdf
  2 -> 456_7_Kriegshaber.pdf
  4 -> 789_Pfersee_Süd.pdf