UNIX for Dummies Questions & Answers

Hi All,
I want to a mathematical callculations as follow:

I have a file FILE1
I want to do following assignment

COUNTER1=`grep -n $string1 FILE1 | cut -d : -f1`
This will give me number of the line on which the string occured.

COUNTER2=`grep -n $string2 FILE1 | cut -d : -f1`
Same as COUNTER1

let i=$COUNTER1-$COUNTER2

It gives an error saying syntax error

Can anyone help on this?

Thanks
VEN

You never said more about what the syntax error said.

Possible reason for the syntax error is multiple occurences of the string1 or string2 which are found.

Check out this code.

It will find 1 occurence for each string1 and string2 and then go ahead.

Code:

#! /bin/sh

COUNTER1=`grep -n $string1 FILE1 | cut -d : -f1`
COUNTER2=`grep -n $string2 FILE1 | cut -d : -f1`

i=$((COUNTER2 - COUNTER1))

echo " Difference of $COUNTER2 and $COUNTER1 is $i "

man grep will help you with other grep options.

Vino

Hi Vino,
I have tried that but even that is not working.
There are no multiple occurences of the string and each grep statement will return only one line.
One thing that amzes me about these mathematical calculations is:
i=10
j=5
let k=$i-$j
This code works fine.
even:
i=`cat file1 | wc -l`
j=`cat file2 | wc -l`
let k=$i-$j
Even this code works.
What problems it has with GREP???
In general I want to know about VARIABLE HANDLING in UNIX script.

I think the root cause of this issue lies in the way UNIX handles variables.

Thanks
Abhijit.

Could you post the exact syntax error and possibly the script you are executing.

Vino

Code:

#!/bin/ksh

# other code here

# note the quoting
let i="$COUNTER1 - $COUNTER2"

# more code

Cheers
ZB