Shell Programming and Scripting

Hello,

I am new to shell scripting. I am running UBUNTU at work and using BASH.

I have this script:

Code:

read M
read R
read T
A=$M+$R+$T
B=2000
if test A -gt B
then
   echo "A is greater than 2000"
else
   echo " A is 2000 or less"
fi

All I am trying to do is to add M, R and T arithmetically and store them in A and then I have to check if A is greater than 2000. If I have A=1 and B=2 and C=3 the value of A is equal to "1+2+3" and not six....

What do I have to do to fix the problem? I feel silly asking this question here but I have looked in books and on the web and what I try does not seem to work.

Hi! If you're doing arithmetic expression, you can do it like the examples below:

Code:

A=`expr $M + $R + $T`

or

Code:

A=$((M+R+T))

I have:

Code:

read M
read R
read T
A=`expr $M + $R + $T`
B=2000
if test A -gt B
then
   echo "A is greater than 2000"
else
   echo " A is 2000 or less"
fi

When I run the script I get:

mohit@mohit-desktop:~$ ./evaluate_mk
1
2
3
./evaluate_mk: line 6: test: A: integer expression expected
A is 2000 or less
mohit@mohit-desktop:~$

I checked and A is an integer and I made B 2000 so that is an integer. What do I do to fix this problem?

When variables are used, they are referred to with the "$" symbol in front of them, so in your test it should be

Code:

if test $A -gt $B

Hi try this code in bash,

read M
read R
read T
A=`expr $M + $R + $T`
B=2000
if [ "$A" -gt "$B" ]; then
echo "A is greater than 2000"
elif [ "$A -lt "$B ];
echo "A is less than 2000"
elif [ "$A" = "$B" ]; then
eho "A is equal to 2000"
fi

Missing a few " quotes there ragavhere.

read M
read R
read T
A=`expr $M + $R + $T`
B=2000
if [ "$A" -gt "$B" ]; then
echo "A is greater than 2000"
elif [ "$A" -lt "$B" ];
echo "A is less than 2000"
elif [ "$A" = "$B" ]; then
echo "A is equal to 2000"
fi