Calculate the sum

Question

Let’s imagine we have a budget document: budget.txt

The exercise is to calculate the sum column for every product in the month, also to calculate totals in the last row. You may try to do it in a shell. How shall it work?

• a program/script shall take a parameter with the filename (not to be hardcoded in the body)
• do the needful
• print output to a screen
• if there’s an error in the data file somewhere, the program/script shall print it on a screen and terminate.

For the bash script, you may try with awk and bc commands.

I have created a shell script

#!/bin/bash
echo -n " Please write the file name:" 
read file 
awk '{print $0}' $file

Answer 1

To demonstrate what Ed was talking about when requesting text ...

And now a pretty-printed, annotated version of the awk bit ...

NR == 1 {                              # print the header line (the 1st row/record)
        print
}

NR > 1 && $0 != "Total" {              # for all but the last record (which starts with "Total")
        rsum = 0                       # zero a tally for the entire row
        for (i = 2; i <= NF; i++) {    # iterate over every column (field) from the 2nd to the last (NF)
                a[i] += $i             # add each fields value to an array (representing the column)
                rsum += $i             # add each fields value to the sum for the row
        }
        printf "%s\t%3d\n", $0, rsum   # print each row with the sum of the row
        fc = NF                        # store the number of fields for the next operation
        a[NF + 1] += rsum              # and tally the grand total
}

$1 == "Total" {                        # for the last row
        printf "Total\t"               # print "Total"
        for (i = 2; i <= fc; i++) {    # then the array values we added up above
                printf "%3d\t", a[i]
        }
        printf "%3d\n", a[fc + 1]      # followed by the grand total
}

Answer 2

You can try this code which is not full proof. But you can make the amendment on this code as per your future requirement. At the moment I have created the budget.txt file and make sure that all the content on it are separated by Tab. After running this script it is providing the below results.

This is the code sample (Note: No value is hard-coded on this script):

#!/bin/bash

function main {
    file_check
    file_content
    calculation
    exit 0
}

function file_check {
    # Asking to provide the file name or complete path. 
    read -p "Enter the file name: " file_name
    
    # Checking if the file exist else exit the script.
    [ -f "$file_name" ] || { echo "The provided file name does not exist. Terminating the script."; exit 0; }
}

function file_content {
    # Saving the file content of first row and column in arrays. 
    column=($(awk '{ print $1 }' "$file_name"))
    row=($(awk 'FNR == 1 { print }' "$file_name"))
    # Calculating the length of the variables.
    column_length=${#column[@]}
    row_length=${#row[@]}
}

function calculation {
    # To calculate the sum of every item per month. 
    for((i=2;i<$row_length;i++)); do
        num=($(awk -v var="$i" '{print $var}' $file_name | sed '1d;$d'))
        sum=$(IFS=+; echo "$((${num[*]}))")
        search_replace_row
    done
    
    # To calculate the last sum of total.
    num=($(tail -1 $file_name | awk '{$1=""}1'))
    sum=$(IFS=+; echo "$((${num[*]}))")
    search_replace_row

    # To calculate sum of single item for every month.
    for ((i=2;i<$column_length;i++)); do
        num=($(awk "FNR == $i { print }" budget.txt | awk '{$1=""}1'))
        sum=$(IFS=+; echo "$((${num[*]}))")
        search_replace_column
    done
}
function search_replace_row {
    content_row=$(tail -1 "$file_name")
    sed -i "s/$content_row/$content_row\t$sum/" $file_name
}
function search_replace_column {
    content_column=$(sed -n "${i}p" $file_name)
    sed -i "s/$content_column/$content_column\t$sum/g" $file_name
}


main