Replace a certain field of the file with the user entry for each row and save to the same file

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Im typing to write a script which can read file_name, delimiter and field_number. After that for each row take an input, replace the field (specified by field_number) and output to same file.

For example if the input is as follows:

Ritesh;M;1992
Shakya;F;1993

For the command

bash_script.sh test.csv ";" 3

Iterating through each row if I input 1994 for first and 1995 for second. I want the output to be the as follows caved in the same file.

Ritesh;M;1994
Shakya;F;1995

So far i managed to get upto this point:

#!/usr/bin/env bash
echo "Following is the input needed:";
echo "\$1: FILE_NAME";
echo "\$2: DELIMITER";
echo "\$3: FIELD IN NUMERIC VALUE";

gawk -i inplace -F "$2" '{...}' $1;

Also my version of gawk doesn't support -i. Thanks in advance.


Answer to first question

If you only need to replace 1992 with 1994 and 1993 with 1995, you don't need a script, you can do it easily using sed:

sed "s/;1992/;1994/g" test.csv | sed "s/;1993/;1995/g"

Output:

[shell] ➤ sed "s/;1992/;1994/g" test.csv | sed "s/;1993/;1995/g"
Ritesh;M;1994
Shakya;F;1995

If you also need to save the output you can add

sed "s/;1992/;1994/g" test.csv | sed "s/;1993/;1995/g" > temp; mv temp test.scv

But if you want to use a script:

#!/bin/bash

if [ -z "${1}" ];then
        echo "Usage: $0 <filename>"
else
        FILENAME=$1
        sed "s/;1992/;1994/g" $FILENAME| sed "s/;1993/;1995/g"
fi

Output:

[shell] ➤ ./test3.sh
Usage: ./test3.sh <filename>

[shell] ➤ ./test3.sh test.csv
Ritesh;M;1994
Shakya;F;1995

Script updated after last comment

#!/bin/bash
if [ -z "${3}" ];then
        echo "Usage: <filename> <delimiter> <field_no>"
else
        FILENAME=$(readlink -f $1)
        DELIMITER=$2
        FIELD_NO=$3
        TEMP_FILE=/tmp/tempFile
        if [ -f $TEMP_FILE ]; then
            rm $TEMP_FILE
        fi
        for line in $(cat $FILENAME)
        do
                oldValue=`echo $line|cut -d$DELIMITER -f$FIELD_NO`
                echo "Enter the value to replace [$oldValue]"
                read newValue
                echo $line | sed "s/${oldValue}/${newValue}/g" >> $TEMP_FILE
        done
fi
mv $TEMP_FILE $FILENAME

I've commented the command #mv tempFile $FILENAME because it's your choice to rename the file or keep the new one.