Watermark Your PDF With A Specific String In Linux

watermark.bash

#!/bin/bash

watermark="${1}"
shift

wm_pdf="$(mktemp -t watermark_XXXXXX.pdf)"

convert -background none -fill "rgba(128, 128, 128, 0.7)" -gravity center -font Arial -pointsize 96 "label:${watermark}" -bordercolor none -border 10x10 "${wm_pdf}"

for input in "$@"; do
    output="$(basename "${input}" .pdf)_wm.pdf"

    qpdf --overlay "${wm_pdf}" --repeat=1 -- "${input}" "${output}"
done