fingerprint.sh

#!/bin/bash

usage() {
  cat <<EOF

  Usage:

  $0 [-r|--recursive] <fname>
  $0 [-h|-?|--help]

  -r --recursive
    recursively descend into a directory, fingerprinting all files

  -h --help -?
    display this message
EOF
}

[[ -z "$CHECKSUM" ]] && CHECKSUM=md5sum

checksum() {
  "$CHECKSUM" "$@" | cut -d' ' -f1
}

fingerprint-recursive() {
  local dirname="$1"; shift

  find "$dirname" -type f | while read fname; do
    fingerprint "$fname"
  done
}

fingerprint() {
  local fname="$1"; shift
  local initpwd="$(pwd)"

  if [[ ! -s "$fname" ]]; then
    echo "$0: $fname does not exist or is not readable.  Aborting."
    return 1
  fi

  local basename="$(basename "$fname")"
  local dirname="$(dirname "$fname")"

  cd "$dirname"

  local checksum="$(checksum "$basename")"

  local base="${basename%.*}"
  local ext="${basename##*.}"

  if [[ "$ext" == "$basename" ]]; then
    ext=""
  else
    ext=".$ext"
  fi

  local fingerprint="$base.$checksum$ext"
  local manifest="$basename.manifest"

  cp "$basename" "$fingerprint"
  echo "$fingerprint" > "$manifest"
  echo "$fingerprint"

  cd "$initpwd"
}

main() {
  local FINGERPRINT=fingerprint

  for arg in "$@"; do
    case "$arg" in
      -r|--recursive) FINGERPRINT=fingerprint-recursive ;;
      -h|-?|--help) usage; return 0 ;;
      *) "$FINGERPRINT" "$arg" ;;
    esac
  done
}

main "$@"