bash-goodies/1dlife

#!/usr/bin/env bash
# Jon Millen's 1D Game of Life in pure Bash (zero dependencies)
# Usage: echo 'state' | 1dlife [iterations]
# Created by Luxferre in 2026, released into public domain

ITERS="$1"
if [[ -z "$ITERS" ]]; then # get the iteration count dynamically
  shopt -s checkwinsize # enable checking the terminal size
  :|: # trigger the WINCH signal to get the size
  ITERS=$((LINES - 1)) # the row count is now in LINES
fi
[[ -z "$RENDER_CHAR" ]] && RENDER_CHAR='#'

# read and process the state
IFS= read -r state
state="${state//[[:space:]]/0}"
state="${state//[^0]/1}"
slen=$((${#state} - 1)) # length + 4 (temporary padding) - 5

# complete rule mapping
declare -A values=(
  00000 0  00001 0  00010 0  00011 1
  00100 0  00101 0  00110 0  00111 1
  01000 0  01001 1  01010 1  01011 1
  01100 0  01101 1  01110 1  01111 0
  10000 0  10001 1  10010 1  10011 1
  10100 0  10101 1  10110 1  10111 0
  11000 1  11001 1  11010 1  11011 0
  11100 1  11101 0  11110 0  11111 1)

for ((i=0; i<ITERS; ++i)); do
  state="00${state}00" # pad the current state from both sides
  newstate=''
  for ((k=0; k<slen; ++k)); do
    vidx="${state:k:5}"
    newstate="${newstate}${values[$vidx]}"    
  done
  state="$newstate"
  newstate="${newstate//0/ }"
  printf '%s\n' "${newstate//1/$RENDER_CHAR}"
done