#!/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, # ------------------------------------------------------# Argument checkARGS=2E_BADARGS=65if [ $# -ne "$ARGS" ]then echo "Usage: `basename $0` first-number second-number" exit $E_BADARGSfi# ------------------------------------------------------gcd (){ # Arbitrary assignment. dividend=$1 # It does not matter divisor=$2 #+ which of the two is larger. # Why? remainder=1 # If uninitialized variable used in loop, #+ it results in an error message #+ on first pass through loop. until [ "$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 |