Usage: ./chshebang [-h|--help] [-f|--force] [-i|--insert] [-d|--dummy] <interpreter> <files> ...
  -f   force replace 1st line with newshell, even it does not start `#!' signature
  -i   insert, instead of replace
  -d   disable intelligent path preparation
  newshell   basename or full path of new interpreter, leading `#!' signature is unnecessary
             eg: /usr/bin/awk, bash, #!/bin/sh
  files      files to modify