#!/bin/bash
#
# Syntax:  pdf_concat_gs [-h] [-o output_file] pdf_files
#
# Purpose: Use gs to concatenate pdf files.
#          Use the -o flag to specify the output file.
#          The -h flag shows the help info for this command.

# Created: Jan  1, 2011       by Bart De Schutter
# Last revised: Dec 30, 2012  by Bart De Schutter
#
# See http://www.deschutter.info/util/scripts.html for the latest version of
# this script.

# Status: public
# Category: pdf

# 
# Define default options
#
output=""

# 
# Process options
#
while getopts :ho: option
do
   case "$option" in
      h) sed '/^$/q;/^#!/d;s/^# //;s/^#//' $0 >&2
         exit 1;;
      o) output="$OPTARG";;
      :) echo >&2
         echo >&2 "Option -$OPTARG requires an argument."
         echo >&2
         sed '/^$/q;/^#!/d;s/^# //;s/^#//' $0 >&2
         echo >&2
         exit 1;;
     \?) echo >&2
         echo >&2 "Unknown option: $OPTARG"
         echo >&2
         sed '/^$/q;/^#!/d;s/^# //;s/^#//' $0 >&2
         exit 1;;
   esac
done
shift $(($OPTIND-1))

if [ $# -eq 0 ];
then
   echo >&2
   echo >&2 "ERROR: ${0##*/} requires at least 1 input argument."
   echo >&2
   sed '/^$/q;/^#!/d;s/^# //;s/^#//' $0 >&2
   exit 1
fi

if [ -z "$output" ];
then
   echo >&2
   echo >&2 "ERROR: The output file has to be specified (via the -o flag)."
   echo >&2
   exit 1
fi

gs -q -sDEVICE=pdfwrite -dNOPAUSE -dBATCH -dSAFER \
   -dPDFSETTINGS=/prepress \
   -dCompatibilityLevel=1.4 \
   -dEmbedAllFonts=true -dSubsetFonts=true -dMaxSubsetPct=100 \
   -dAutoFilterColorImages=false -dAutoFilterGrayImages=false \
   -dColorImageFilter=/FlateEncode -dGrayImageFilter=/FlateEncode \
   -dAutoFilterMonoImages=false -dMonoImageFilter=/CCITTFaxEncode \
   -sOutputFile="$output" \
   "$@"

# Extra option: -sPAPERSIZE=a4
#               -dPDFSETTINGS=/prepress