CODEWITHSUNDEEP
bashshellnumbersecho
user6223604
user6223604

Reputation:

Shell : How to do minus between number

I want to subtract a list of values from a number.

I tried:

DATACOME=1013
DATAREF=1010
1020

var=$((DATACOME - DATAREF))
echo "$var"
3

It works just for the first value in $DATAREF and outputs 3 instead of:

echo "$var"
3
-7

Upvotes: 0

Views: 672

Answers (1)

PesaThe
PesaThe

Reputation: 7509

Straightforward approach is to save the list of values as an array dataref and then iterate over it with a for loop:

datacome=1013
dataref=(1010 1020)

for num in "${dataref[@]}"; do
   echo $((datacome - num))
done

If you don't want to use arrays, you can store your values in a string separated by whitespace characters and use awk:

datacome=1013
dataref="1010 1020" 

awk -v num="$datacome" '{
    for (i = 1; i <= NF; i++) {
        print num-$i
    }
}' <<< "$dataref"

Or again with a for loop using word-splitting this time:

datacome=1013
dataref="1010
1020" 

for num in $dataref; do
   echo $((datacome - num))
done

Or when using a file to store your values:

#input_file:
#1010
#1020

datacome=1013

while read num; do
   echo $((datacome - num))
done < input_file    

awk -v num="$datacome" '{
    for(i = 1; i <= NF; i++) {
        print num-$i
    }
}' < input_file

EDIT: on @dawg's recommendation, this is one of many possible ways to do this with bc:

datacome=1013
dataref="1010 1020" 

for num in $dataref; do
   echo "$num-$datacome"
done | bc -l

There really are a lot of ways to do this. Also, please do not use uppercase variables as they could collide with environment and internal shell variables.

Upvotes: 1

Related Questions