PDF compression CLI with Ghostscript.

pdf-compress.sh

pdf-compress() {
    QUALITY=150
    INPUT_PDF=""
    GS_BIN=$(command -v gs)

    print_usage() {
        echo "Usage: pdf-compress [-q|--quality <res>] <file>"
        echo "    Where:"
        echo "        -q|--quality <res> is the resolution for the PDF (default: 150)"
        echo "        <file> is the PDF file to compress"
    }

    if [ -z "$GS_BIN" ]; then
        echo "Please make sure Ghostscript (gs command) is installed and available in PATH."
        return 1
    fi
    
    while [ "$1" != "" ]; do
        case $1 in
            -h | --help)
                print_usage
                return 0
                ;;
            -q | --quality)
                shift
                if [[ $1 =~ ^[0-9]+$ ]] ; then
                    if [ "$1" -gt 300 ] || [ "$1" -lt 50 ]; then
                        echo "Invalid quality: $1. Quality should be between 50 and 300."
                        return 1
                    else
                        QUALITY=$1
                    fi
                else
                    echo "Invalid quality: $1. Quality should be a number."
                    return 1
                fi
                ;;
            *)
                INPUT_PDF=$1
                ;;
        esac
        shift
    done

    if [ -z "$INPUT_PDF" ]; then
        echo "Please specify the PDF file to compress."
        print_usage
        return 1
    elif [ ! -f "$INPUT_PDF" ]; then
        echo "File $INPUT_PDF does not exist."
        return 1
    fi

    GS_ARGS="-sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/screen -dNOPAUSE -dBATCH -dColorImageResolution=$QUALITY -dGrayImageResolution=$QUALITY -dMonoImageResolution=$QUALITY -sOutputFile=output.pdf"

    $GS_BIN $GS_ARGS "$INPUT_PDF"
}