Advanced Bash−Scripting Guide

Advanced Bash−Scripting Guide
# 4*5 #
# 678 #
# #
# 2) A living cell with either 2 or 3 living neighbors remains alive. #
# 3) A dead cell with 3 living neighbors becomes alive (a "birth"). #
SURVIVE=2 #
BIRTH=3 #
# 4) All other cases result in dead cells. #
# ##################################################################### #
startfile=gen0 # Read the starting generation from the file "gen0".
# Default, if no other file specified when invoking script.
#
if [ −n "$1" ] # Specify another "generation 0" file.
then
if [ −e "$1" ] # Check for existence.
then
startfile="$1"
fi
fi
ALIVE1=.
DEAD1=_
# Represent living and "dead" cells in the start−up file.
# This script uses a 10 x 10 grid (may be increased,
#+ but a large grid will will cause very slow execution).
ROWS=10
COLS=10
GENERATIONS=10
NONE_ALIVE=80
TRUE=0
FALSE=1
ALIVE=0
DEAD=1
avar=
generation=0
# How many generations to cycle through.
# Adjust this upwards,
#+ if you have time on your hands.
# Exit status on premature bailout,
#+ if no cells left alive.
# Global; holds current generation.
# Initialize generation count.
# =================================================================
let "cells = $ROWS * $COLS"
# How many cells.
declare −a initial
declare −a current
# Arrays containing "cells".
display ()
{
alive=0
# How many cells "alive".
# Initially zero.
declare −a arr
Appendix A. Contributed Scripts 380