UNIX for Dummies Questions & Answers

Hi this is quite a simple question... I am new to LINUX/UNIX and so I am just trying to create a very basic program. The idea is that when the user runs the program (from the shell) they enter 3 values and the program will add them up:
"./sum 23 5 1
29"
my code for this program is as follows:

Code:

if [ $# -eq 0 ]
then
    echo "no values entered"
    exit 1
else
    sum=0
    sum=`expr $1 + $2 + $3`
    echo "$sum"
fi

However I now want to allow for more than 3 values to be entered. I have done a bit of research and I think the best way is to use a 'for loop' that will tally the numbers:

Code:

for a in $*
  ???
done
exit 0

As you can see I don't really know where to include this in my program nor how to write it. Like I said I am a beginner to UNIX and so any help would be greatly appreciated!
Thanks
-James

You are almost there:

Code:

sum=0
for a in $*
do
  ???
done

In the loop the variable a' will contain the consecutive values, so just keep adding $a to sum.

thank you, however I have tried that method using code similar to:

for a in $*
do
total=`expr $sum + a`
echo "$total"
done

is this what you meant? If so then I have found it delivers the following output:

./sum 2 4 5 5 12 //user has entered 5 numbers
11 //sum of the first three
16 //sum of the first three plus the fourth
23 //sum of the first three plus the fifth

as you can see it does the usual 'sum' equation then adds each value to the first 3 individually. I need them all to be totalled. Any ideas?
Thank you again
-James

Actually what I meant was this

Code:

sum=0
for a in $*
do
  sum=$(( sum + a ))
done

Thank you for the help =]