docker-mailserver/target/bin/sedfile

#!/bin/bash

# Wrapper for 'sed -i': fail if file was not modified by sed and container was not restarted.
# Error output is surpressed, when container is restarted to avoid harmless error messages.
# Use "--strict" as first parameter, to fail regardless of the container state (fresh or restarted).

# When to use sedfile?
# Is a file change optional? --> use regular 'sed -i'
# Is a file change expected? --> use 'sedfile --strict -i'
# Is a file change only on the first container run expected? --> use 'sedfile -i'

set -ueo pipefail

HASHTOOL="sha1sum"
SKIP_ERROR=0

if [[ $# -lt 3 ]]
then
  echo "Error:  At least, three parameters must be given."
  echo "Syntax: sedfile -i <replace/delete operation> <file>"
  echo
  exit 1
fi >&2

[[ -f /CONTAINER_START ]] && SKIP_ERROR=1 # Hide error, if container was restarted.
if [[ "${1}" == "--strict" ]]         # Show error every time.
then
  SKIP_ERROR=0
  shift
fi

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

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

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

exit 0