How to preserve bookmarks when rearranging pages of a PDF file with tools like pdftk?

pdf-cut-first-page.sh

#!/bin/sh


##
# from: https://unix.stackexchange.com/questions/17045/how-to-preserve-bookmarks-when-rearranging-pages-of-a-pdf-file-with-tools-like-p
#

pdftk A=in.pdf cat A2-end output temp.pdf

pdftk in.pdf dump_data > in.info

cat > ins.php <<EOF
<?php
$file = "in.info";
$data = file_get_contents($file);


foreach (explode("\n", $data) as $row) {
    $tmp = explode(": ", $row);

    if ($tmp[0] == "BookmarkPageNumber") {
        if ($tmp[1] != "1") $tmp[1]--;
        echo $tmp[0].": ".$tmp[1]."\n";
    } else {
        echo $row."\n";
    }
}
?>
EOF

php ins.php > in2.info

grep -B3 'BookmarkPageNumber: 1$' in2.info

pdftk temp.pdf update_info in2.info output out.pdf