pagenum

#!/bin/bash

usage_exit(){
    echo "usage: pagenum [-o offset] file.pdf" 1>&2
    exit 1
}

pagenum_ps(){
cat <<EOT
/input (%stdin) (r) file def
/input_buffer 2048 string def
/cshow { dup stringwidth pop 2 div neg 0 rmoveto show } def
/showpage {
    input input_buffer readline pop cvx exec
    systemdict /showpage get exec
} def
EOT
}

offset=0
while getopts o: OPT ; do
    case $OPT in
    o) offset=$OPTARG ;;
    *) usage_exit ;;
    esac
done

shift `expr $OPTIND - 1`

file=$1
[[ -z $file ]] && usage_exit

pdf2ps $file temp.ps

for i in $(seq 1 $(pdfinfo $file | grep -a "^Pages:" | sed "s/[^0-9]//g")); do
pagenum=$((offset + i))
xargs -d '\n' <<EOT
    gsave
    /Helvetica findfont 10 scalefont setfont
    $pagenum 2 mod 0 eq { 50 } { 464 } ifelse 30 moveto
    ($pagenum) cshow
    grestore
EOT
done | gs -sDEVICE=pdfwrite -sOutputFile=output.pdf -dNOPAUSE -dBATCH -q <(pagenum_ps) temp.ps

rm temp.ps

pagenum.ps

/input (%stdin) (r) file def
/input_buffer 2048 string def
/cshow { dup stringwidth pop 2 div neg 0 rmoveto show } def
/showpage {
    input input_buffer readline pop cvx exec
    systemdict /showpage get exec
} def