Elementary Cellular Automata in POSIX Shell, Rules from 0 to 255

eca.sh

#!/bin/sh

cnum=180; step=80;

rule=0
while [ $rule != 256 ]; do
  b=$rule; for x in 0 1 2 3 4 5 6 7; do export r$x=$((b%2)) b=$((b/2)); done

  i=0; while [ $i != $cnum ]; do export c$i=0 i=$((i+1)); done
  export c$((cnum/2))=1
  clear

  s=0
  while [ $s != $step ]; do
    i=0
    while [ $i != $cnum ]; do
      case $((c$i)) in 0) printf " ";; *) printf "*";;
      esac; i=$((i+1))
    done
    echo

    i=0
    while [ $i != $cnum ]; do
      case $i in 0) x=0;; *) x=$((c$((i-1))));; esac
      y=$((c$i))
      case $i in $((cnum-1))) z=0;; *) z=$((c$((i+1))));; esac
      export cn$i=$((r$((x*4+y*2+z)))) i=$((i+1))
    done

    i=0; while [ $i != $cnum ]; do export c$i=$((cn$i)) i=$((i+1)); done
    s=$((s+1))
  done

  sleep 0.1
  rule=$((rule+1))
done