pdfmerge

#!/bin/sh
help() { cat <</help
Merge PDF and similar files (PDF, PS, and TIFF) using Ghostscript
Usage: pdfmerge [ OPTIONS ] [ INPUT ... ]
  -o OUTPUT      Type is determined by extension: .pdf (default), .tiff, or .ps
  -D DEVICE      Override output format with a ghostscript device
  -V, --verbose  Verbose output
  -x EXECUTABLE  Alternate name or path for ghostscript

This is a drop-in replacement for the old psmerge program

/help
  version
}

version() {
  echo 'Part of misc-scripts: https://github.com/adamhotep/misc-scripts'
  echo 'pdfmerge 0.7.20240810.0, Copyright 1999+ by Adam Katz, GPL v2+'
  exit
}

die() { echo "$*" >&2; exit 2; }	# complain to STDERR and exit with error

needs_arg() { if [ -z "$OPTARG" ]; then die "No arg for --$OPT option"; fi; }

device=""		# default to be set later as a fallback
ghostscript="gs"	# default ghostscript command
quiet="-q"		# default: quiet (disabled with verbose)

while getopts D:ho:vVx:-: OPT; do
  if [ "$OPT" = - ]; then # long opt https://stackoverflow.com/a/28466267/519360
    OPT="${OPTARG%%=*}" OPTARG="${OPTARG#$OPT}" OPTARG="${OPTARG#=}"
  fi
  case "$OPT" in
    ( D | device )	needs_arg; device="$OPTARG" ;;
    ( h | help )	help ;;
    ( o | out* )	needs_arg; out="$OPTARG" ;;
    ( V | verb* )	quiet="" ;;
    ( v | ver* )	version ;;
    ( x | exe* | gs* )	ghostscript="$OPTARG" ;;
    ( ??* )		die "Illegal option --$OPT" ;; # bad long option
    ( ? )		exit 2 ;; # bad short option (error reported via getopts)
  esac
done
shift $((OPTIND-1))

if ! command -v "$ghostscript" >/dev/null 2>&1; then
  if [ "$ghostscript" = "${ghostscript#*/}" ]; then inpath=" in PATH='$PATH'"; fi
  die "No Ghostscript executable found (tried '$ghostscript'$inpath), aborting"
fi

if [ -s "$out" ]; then
  echo -n "${0##*/}: Overwrite existing output file \`$out' [yN]? "; read YN
  [ "${YN#[yY]}" = "$YN" ] && echo "${0##*/}: Merge cancelled." && exit 1
fi

if [ -z "$device" ]; then
  case ${out##*.} in # file ext dictates type; see  gs -h|sed '/devices:/,/^[^ ]/!d'
    ( PS | ps )			device="pswrite" ;;
    ( TIFF | tiff | TIF | tif )	device="tiffg3" ;;
    ( * ) 			device="pdfwrite -dCompatibilityLevel=1.2" ;;
  esac
fi

exec gs $quiet -dNOPAUSE -dBATCH -sDEVICE=$device -sOutputFile="${out:--}" "$@"