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Shell Programming and Scripting

help - scripting command

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# 1  
Old 11-28-2011
help - scripting command
hello

I'n new to the unix environment Smilie
I'm trying to script a command that takes 2+ integers and adds them together in bash.

eg

$ add 10 12 13
35

probably kind of basic but i also have to verify that they are indeed integers and that the "add" command has at least 2 parameters.

any ideas?
# 2  
Old 11-28-2011
Code:
#! /bin/bash

if [ $# -lt 2 ]
then
    echo "Less than 2 paramaters"
    exit
fi

# The below if condition checks if the number contains a decimal point or not.
# Actually in the for-loop below expr used will not work if the number is not an integer. If you try doing "expr 1.1 + 2.2", it'll say something like this: "expr: non-numeric argument"

echo $* | grep -qe "\."
if [ $? -eq 0 ]
then
    echo "One of the input in not an integer"
    exit
fi

sum=0
for x in $@
do
    sum=`expr $sum + $x`
done

echo "The sum is $sum"

# 3  
Old 11-28-2011
awesome i will try this out!

thanks!
# 4  
Old 11-28-2011
Quote:
Originally Posted by balajesuri
Code:
# The below if condition checks if the number contains a decimal point or not.
# Actually in the for-loop below expr used will not work if the number is not an integer. If you try doing "expr 1.1 + 2.2", it'll say something like this: "expr: non-numeric argument"

echo $* | grep -qe "\."
if [ $? -eq 0 ]
then
    echo "One of the input in not an integer"
    exit
fi

sum=0
for x in $@
do
    sum=`expr $sum + $x`
done

echo "The sum is $sum"


There's no need for external commands (grep and expr).

Use a function to determine whether an argument is an integer:
Code:
is_int()
{
  case $1 in
    *[!0-9]*|"") return 1 ;;
  esac
}

Then check each arg before using it:
Code:
total=0
for int
do
  is_int "$int" || exit 1
  total=$(( $total + $int ))
done
printf "Total: %s\n" "$total"

# 5  
Old 11-29-2011
thanks
# 6  
Old 11-29-2011
is there a way after the "then" to just continue in the script without displaying the error message?

Code:
if [ $? -eq 0 ]
then
    echo "One of the input in not an integer"
    exit
fi

# 7  
Old 11-29-2011
If you just want to continue in the script, why would you want a check to see if the number is an integer or not. Remove the whole if-block.
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