pdfmetaedit

#!/usr/bin/env bash
#
# NAME
#
#   pdfmetaedit - edit metadata of PDF files
#
# SYNOPSIS
#
#   pdfmetaedit [-a] <file>
#
# OPTION
#
#       -a      use the filename as the PDF title
#
# DESCRIPTION
#
#   pdfmetaedit is a wrapper script around PDFtk that will let you edit the
#   metadata (e.g., "subject", "title", etc.) of PDF files using $EDITOR.
#
# DEPENDENCIES
#
#   pdftk(1) and mktemp(1)
#

set -eu
set -o pipefail

tmpdir="$(mktemp -d)"
trap 'rm -rf "$tmpdir" &>/dev/null' EXIT
trap 'exit 2' HUP INT QUIT TERM

auto="no"
while getopts ":a" opt
do
    case "$opt" in
        a)  auto="yes" ;;
        \?) echo >&2 "${0##*/}: -$OPTARG is not a valid option\n"
            exit 1 ;;
    esac
done
shift $(( OPTIND - 1 ))

[[ "$*" ]] || {
    echo >&2 "usage: ${0##*/} [-a] <file>"
    exit 1
}

meta="${tmpdir}/meta.txt"

if [[ "$auto" == "yes" ]]
then
cat >"$meta" <<META
  InfoBegin
  InfoKey: Title
  InfoValue: $1
META
else
    pdftk "$1" dump_data_utf8 | grep '^Info' | sed '/^InfoBegin/! { s/^/  /; }' >"$meta"

    # Generate these default keys if they're not available.
    for key in "Author" "Subject" "Title" "Keywords"
    do
        grep -q "InfoKey: ${key}" "$meta" || {
            echo "InfoBegin"
            echo "  InfoKey: ${key}"
            echo "  InfoValue:"
        } >>"$meta"
    done

    "${EDITOR:-vi}" "$meta"
fi

pdf="${tmpdir}/updated.pdf"
pdftk "$1" update_info_utf8 <(sed 's/^ *Info/Info/' "$meta") output "$pdf"
mv -f "$pdf" "$1"