gen_pdf_overlay_footer

#!/usr/bin/env bash

die() { printf %s "${@+$@$'\n'}" 1>&2 ; exit 1 ; }
see() ( { set -x; } 2>/dev/null ; "$@" )
dieifnotinpath() { command -v "$1" >/dev/null || die "$1 not in PATH"; }

#
# Usage:
#   ./make_footer_watermark.sh "Left footer text" "Right footer text"

LEFT="$1"
RIGHT="$2"

cat <<'END_PS' > watermark.ps
%!PS
% Set page size to letter (612x792); adjust if needed
<< /PageSize [612 792] >> setpagedevice

/Helvetica findfont 12 scalefont setfont

% Bottom margin
36 dup translate  % Move origin 36pt right, 36pt up
0 0 moveto

% We'll define a helper procedure to show text on the right side
% of the page. 'showright' is a custom operator that measures the string,
% then places it from the right margin minus 36pt.
/showright {
   % 0 index => (string)
   dup stringwidth pop            % measure width
   612 exch sub                   % 612 = page width; subtract string width
   72 sub                         % subtract 72 for the right margin
   0 moveto
   show
} def

% Left text
(%LEFT_TEXT%) show

% Move to the same baseline, but we reset x
0 0 moveto

% Right text
(%RIGHT_TEXT%) showright

showpage
END_PS

# Replace placeholders with our 2 arguments (escape if necessary!)
sed -i "s|%LEFT_TEXT%|${LEFT}|" watermark.ps
sed -i "s|%RIGHT_TEXT%|${RIGHT}|" watermark.ps

# Use Ghostscript to produce a PDF
gs \
  -sDEVICE=pdfwrite \
  -dCompatibilityLevel=1.4 \
  -dPDFSETTINGS=/screen \
  -o watermark.pdf \
  -f watermark.ps

echo "Created watermark.pdf"