3 numbers and return the maximum

Shell Programming and Scripting
1

Hello,
I am doing bash and for that doing excersices. The folowing one asks for 3 numbers and is suppose to return the maximum. An error should be returned if on of the numbers is missing. I managed to solve it. Can you give me other ways or advices.

#!/bin/bash
#Date: 2010.10.19
#Ecrire un script qui prend en param�e trois entiers et qui affiche le plus grand. On affichera un message d'erreur s'il n'y pas pas trois arguments pass�sur la ligne de commande

echo "Entree trois entiers; separee par un espace";read numb1 numb2 numb3

MAX="0"

for i in $numb1 $numb2 $numb3 ; do
    echo "$i"
    if [ $MAX -lt $i ] ; then
        MAX=$(echo $i)
    fi
done

echo "Le plus grand nombre est: $MAX"

#END
2

You could do something like:

for i in $numb1 $numb2 $numb3 ; do
    echo "$i"
    if [ `echo "$i" | awk '{ print (int($0)==$0)}'` == 0 ]; then 
       echo "$i" is not numeric
       exit 1
    fi
    if [ $MAX -lt $i ] ; then
        MAX=$(echo $i)
    fi
done
3 
echo "Entree trois entiers; separee par un espace";read numb1 numb2 numb3

MAX=0
counter=0

for i in $numb1 $numb2 $numb3 ; do
    echo "$i"
    counter=$(( ${counter} + 1 ))
    if [ $MAX -lt $i ] ; then
        MAX=$(echo $i)
    fi
done

if [ ! $counter -eq 3 ]
then
    echo "Please enter 3 numbers (not ${counter} numbers)"
else
    echo "Le plus grand nombre est: $MAX"
fi
4

Added test for 3 values (uses array numbs) and test value entered is numeric. Errors printed to stderr and exit status set.

#!/bin/bash
#Date: 2010.10.19
#Ecrire un script qui prend en param�e trois entiers et qui affiche le plus grand. On affichera un message d'erreur s'il n'y pas pas trois arguments pass�sur la ligne de commande
echo "Entree trois entiers; separee par un espace";read -a numbs
MAX="0"
if [ ${#numbs[@]} -ne 3 ]
then
    echo "Error: 3 numbers required" >&2
    exit 1
fi
for i in ${numbs[@]} ; do
    if [ $i -gt 0 ] 2> /dev/null || [ $i -le 0 ] 2> /dev/null
    then
        if [ $MAX -lt $i ] ; then
            MAX=$i
        fi
    else
        echo "Error: $i is not numeric" >&2
        exit 2
    fi
done
echo "Le plus grand nombre est: $MAX"
5

Thanx to all I have reviewed all you solutions. I learned a great deal.

@Chubler_XL

What is this test for. and why do you send to /dev/null?

BR.

---------- Post updated at 03:58 AM ---------- Previous update was at 03:56 AM ----------

thx for the Solution. But I don't know how tu use awk yet. But you did not include the test for 3 numbers.
BR.

6

Alternatively tou could use a case statement, for example:

for i in $numb1 $numb2 $numb3 ; do
    case $i in *[^0-9]*)
      echo "$i" is not numeric
      exit 1
    esac
    if [ $i -gt $MAX ] ; then
      MAX=$i
    fi
done
echo $MAX