Hello fellow UNIX gurus 
I have a problem regarding the script below:
# Variables used in this shell.
power=0 # Stores squared integer
total=0 # Sum of all squared integers
num=0 # Stores command line arguements
# Provides error handling if command line arguments are 0.
if [ $# = 0 ]; then
echo "Usage $0 - integer-list"
exit 1
fi
# Function that is used to sum all integers values
# from the power variable; store the sum in total variable.
sum()
{
total=`expr $total + $power`
}
# Iterate through the command line arguments, and store
# each integer in $num.
for num in $@; do
if [ $num -ge 1 -a $num -le 65536 ]; then
# $num squared stored in power variable.
power=`expr $num \* $num`
# Output computation result.
echo "$num squared equals = $power"
# Call sum() function to evaluate the sum of
# squared integers.
sum
# Else, if argument is over 65536, print user notification that
# the maximum number has been reached.
elif [ $num -ge 65536 ]; then
echo "65536 is the maximum number for this script"
exit 1
# Otherwise; when the arguments are not in range of 0-65536,
# prompt user why shell executes prematurely.
else
# User notification.
echo "$num is an invalid argument. Only natural numbers from 0 to 65536 are valid."
# Exit shell script.
exit 1
fi
done
# Print out the sum of the sqaured number list.
echo "Total sum of the squared integers: $total"
# Exit shell script.
exit 0
Everything runs fine except when I type in a sting as argument I get the following error:
[: 63: Illegal number: string
I want that whatever input is provided a custom error message is printed instead of that error code above. Any hints on that are greatly appreciated.
-Daniel