#!/bin/bash# gcd.sh: greatest common divisor#         Uses Euclid's algorithm#  The "greatest common divisor" (gcd) of two integers#+ is the largest integer that will divide both, leaving no remainder.#  Euclid's algorithm uses successive division.#  In each pass,#+ dividend <---  divisor#+ divisor  <---  remainder#+ until remainder = 0.#+ The gcd = dividend, on the final pass.##  For an excellent discussion of Euclid's algorithm, see#+ Jim Loy's site, http://www.jimloy.com/number/euclids.htm.# ------------------------------------------------------# Argument checkARGS=2E_BADARGS=65if [ $# -ne "$ARGS" ]then  echo "Usage: `basename $0` first-number second-number"  exit $E_BADARGSfi# ------------------------------------------------------gcd (){  dividend=$1             #  Arbitrary assignment.  divisor=$2              #! It doesn't matter which of the two is larger.                          #  Why not?  remainder=1             #  If uninitialized variable used in loop,                          #+ it results in an error message                          #+ on the first pass through loop.  until [ "$remainder" -eq 0 ]  do    let "remainder = $dividend % $divisor"    dividend=$divisor     # Now repeat with 2 smallest numbers.    divisor=$remainder  done                    # Euclid's algorithm}                         # Last $dividend is the gcd.gcd $1 $2echo; echo "GCD of $1 and $2 = $dividend"; echo# Exercise :# --------#  Check command-line arguments to make sure they are integers,#+ and exit the script with an appropriate error message if not.exit 0