#!/usr/bin/tclsh8.0

proc header {file {gridSize 1} {units pc} {weight 0.1}} {
puts $file \
"%!PS-Adobe-2.0
/GridSize $gridSize def
/Units {$units} def
/Weight {$weight} def
"
}

set gridSize 1
set units pc
set weight 0.1

foreach arg $argv {
    switch -glob $arg {
	gridSize=* { set gridSize [string range $arg 9 end] }
	units=* { set units [string range $arg 6 end] }
	weight=* { set weight [string range $arg 7 end] }
	default { set filename $arg }}}

if [info exists filename] \
    { set file [open $filename w] } \
    { set file stdout }
    
header $file $gridSize $units $weight
puts $file {
gsave
initclip clippath pathbbox
/PageHeight exch def
/PageWidth exch def
pop pop
grestore

/in { 72 mul } def
/pt { 1 mul } def
/pc { 12 mul } def
/mm { 2.8346 mul } def

/gridDistance GridSize Units def
/nGridsWide PageWidth gridDistance div floor cvi def
/nGridsHigh PageHeight gridDistance div floor cvi def
/useWide gridDistance nGridsWide mul def
/useHeight gridDistance nGridsHigh mul def

/toStart {
  PageWidth useWide sub 2 div
  PageHeight useHeight sub 2 div
  moveto
  } def

Weight setlinewidth
toStart
0 1 nGridsWide {
  0 useHeight rlineto
  gridDistance useHeight neg rmoveto
  } for
stroke

toStart
0 1 nGridsHigh {
  useWide 0 rlineto
  useWide neg gridDistance rmoveto
  } for
stroke

showpage
}