[Explain motivation (cron, possible sneer at Java, portability, ...]
[Explain alternatives:
#! /usr/local/bin/tclsh8.3 puts "Content-Type: image/x-portable-graymap" puts "" puts "P2" ;# ASCII PGM "magic number" puts "10 10" ;# width and height puts "18" ;# Max grey value for {set i 0} {$i<10} {incr i} { set line "" for {set j 0} {$j<10} {incr j} { lappend line [expr {$i+$j}] } puts $line } exit
See also "strimj - string image routines" and "barchart". GIF has code snippets for writing image files in pure Tcl.