combine_pdf.sh

#!/usr/bin/env bash

set -e -o nounset

PDFTK_PATH="$HOME/src"
PDFTK_URL="https://gitlab.com/pdftk-java/pdftk/-/jobs/517065828/artifacts/raw/build/libs/pdftk-all.jar?inline=false"

if ! [ -d "$PDFTK_PATH" ]
then
    printf "Creating the src path to install the pdftk-all tool"
    mkdir -p "$PDFTK_PATH"
fi

if ! command -v curl > /dev/null 2>&1
then
    printf "Not able to find the curl command on this system."
    printf "Please download this file manually and place it into the %s" "$PDFTK_PATH"
    printf "%s" "$PDFTK_URL"
    exit 1
fi

if ! [ -f "$PDFTK_PATH/pdftk-all.jar" ]
then
    printf "The pdftk-all tool was not found, downloading a new copy"
    curl "$PDFTK_URL" -s -o "$PDFTK_PATH/pdftk-all.jar"
fi

if ! command -v java > /dev/null 2>&1
then
    printf "The java command wasn't found on your system, trying to install it."
    curl "https://github.com/AdoptOpenJDK/openjdk10-binaries/releases/download/jdk-10.0.2%2B13.1/OpenJDK10U-jre_x64_mac_hotspot_10.0.2_13.tar.gz" -L -s -o "$PDFTK_PATH/OpenJDK10U-jre_x64_mac_hotspot_10.0.2_13.tar.gz"
    cd "$PDFTK_PATH" || exit 1
    tar xzf OpenJDK10U-jre_x64_mac_hotspot_10.0.2_13.tar.gz
    rm OpenJDK10U-jre_x64_mac_hotspot_10.0.2_13.tar.gz
    export PATH=$PATH:"$PDFTK_PATH/jdk-10.0.2+13-jre/Contents/Home/bin"
    export JAVA_HOME="$PDFTK_PATH/jdk-10.0.2+13-jre/Contents/Home"
    java -version
    cd - || exit 1
else
    if [ -f combined.pdf ]
    then
	printf "\n\nThis tool will create a file called combined.pdf and a file with\n"
	printf "that name was already found here: %s/combined.pdf\n\n" "$PWD"
	printf "Please rename or remove this combined.pdf file."
	exit 1
    fi
    if [ $# -eq 0 ]
    then
	printf "\n\nType in the names of the PDF files to be combined after the name of the program seperated by a spaces.\n\n"
	printf "Make sure to use 'quotes' around any filename with a space already in it.\n\n\n"
	printf "Example: %s my_file.pdf 'My Other Document.PDF' somefile.pdf" "$0"
	exit 1
    fi
    
    java -jar "$PDFTK_PATH/pdftk-all.jar" "$@" cat output combined.pdf
    printf "Done!  Created: %s/combined.pdf\n\n" "$PWD"
fi