#!/bin/bash

# wrapper for 'sed -i': fail if file was not modified by sed

set -ueo pipefail

HASHTOOL="sha1sum"

if [[ $# -lt 1 ]]
then
  echo "Error: No file given."
  echo
  exit 1
fi >&2

# get last argument
FILE=${*: -1}

OLD=$(${HASHTOOL} "${FILE}")
sed "$@"
NEW=$(${HASHTOOL} "${FILE}")

# fail if file was not modified
if [[ ${OLD} == "${NEW}" ]]
then
  echo "Error: sed $*"
  exit 1
fi >&2
exit 0