A script that recognizes some input errors

pvictory1 · 11-15-2009, 01:50 PM

Hello this is my first time posting and what I can't figure out is I need to add into the script to make it recognize some input errors and I just do know how to do this. Please help

Code:

#This program accepts three numbers and shows the largest of them
#
echo
echo "Enter three numbers and I will show you the largest>> \c
read num1 num2 num3
if test "$num1" -gt "$num2" -a "$num1" -gt "$num3"
then 
   echo "The largest number is: $num1"
elif test "$num2" -gt "$num1" -a "$num2" -gt "$num3"
then
   echo "The largest number is:$num2"
else
   echo "The largest number is:$num3"
fi 
echo "done!"
echo
exit 0

unSpawn · 11-15-2009, 04:56 PM

Welcome to LQ.

Quote:

Originally Posted by pvictory1

make it recognize some input errors

- Exactly what type of errors should it recognize (numbers equal or greater than 100, strings, carriage returns, empty $#, what)?
- What have you tried and in what way did it not work (post code and errors)?

Code:

function help() { echo "${FUNCNAME}: Bash scripting guides:
http://www.tldp.org/HOWTO/Bash-Prog-Intro-HOWTO.html 
http://www.tldp.org/LDP/Bash-Beginners-Guide/html/index.html 
http://www.tldp.org/LDP/abs/html/; }

DaveQB · 11-15-2009, 05:08 PM

To check what is entered is a number, you could do it a number of ways.

One way to to search it.

echo $num | grep [[:alpha:]]
if [ "$?" -eq 1 ]
then
echo You entered a number.
fi

Or you could just use

Z=$((num1 + 1))
if [ "$?" -eq 0 ]
then
echo You entered a number.
fi