PoC for https://github.com/chaudum/rgain/issues/30

replaygain

#!/bin/bash
# This is a wrapper that adds one option to rgain3's replaygain script
# replaygain-wrapper version 0.1, Copyright (C) 2020+ by Adam Katz <@adamhotep>
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# Full license: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html

real="/usr/bin/replaygain"

help() {
  "$real" --help
  echo "  -t, --preserve-times  Keep files' original timestamps"
  echo "  -x, --executable=FILE Use this instead of '$real'"
  exit
}

# the revised list of arguments (for the real program)
args=()

while getopts dfhr:tx:-: OPT; do
  # support long options: https://stackoverflow.com/a/28466267/519360
  if [ "$OPT" = - ]; then
    OPT="${OPTARG%%=*}" OPTARG="${OPTARG#$OPT}" OPTARG="${OPTARG#=}"
  fi
  case $OPT in
    ( d | dry-run )
      args+=(--dry-run)
      NO_OP=true ;;
    ( h | help )
      help ;;
    ( show )
      args+=(--show)
      NO_OP=true ;;
    ( t | preserve-time* )
      PRESERVE_TIMES=true ;;
    ( x | exe* )
      real="$OPTARG" ;;
    ( ??* )	# other long option
      if [ -z "$OPTARG" ]
        then args+=("--$OPT")
        else args+=("--$OPT=$OPTARG")
      fi
      ;;
    ( * )	# other short option
      args+=("-$OPT")
      if [ -n "$OPTARG" ]; then args+=("$OPTARG"); fi
  esac
done
# remove options as originally provided, then prepend revised list (if any)
shift $((OPTIND-1))
set -- ${args+"${args[@]}"} "$@"

if [ "$NO_OP" = true ]; then
  PRESERVE_TIMES=false
elif [ "$PRESERVE_TIMES" = true ]; then
  TMP="$(mktemp ${TMPDIR:-/tmp}/rgain.$$.XXXXX.sh)"
  trap "rm -f $TMP" 0 1 2 5 9 11 15 18
  if stat -c %Y / >/dev/null 2>&1; then	# GNU coreutils (stat & date)
    when() { date -d@"$(stat -c %Y "$@")" +%Y%m%d%H%M.%S; }
  else	# BSD stat & date
    when() { date -jf %s "$(stat -f %m "$@")" +%Y%m%d%H%M.%S; }
  fi
  for input in "$@"; do
    echo "$(when "$input")=$input" >> $TMP
  done
fi

"$real" "$@"
retval=$?

if [ "$PRESERVE_TIMES" = true ]; then
  cat $TMP | while IFS= read -r line; do
    touch -t "${line%%=*}" "${line#*=}"
  done
fi

exit $retval