How could I add new string while keeping the tab line?

user_6012546 0
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I tried to add new string using shell script when the code line have "MSG_LOG". I did add new string at the new line using this shell script,

#!/bin/bash

############Set File Name
fileName=$1
echo ">>>>Set_FileName is done"
echo ">>>>fileName is    ${fileName}"

############Get Elements
lineNumArr=(`grep -n "MSG_LOG" $fileName | awk -F ':' '{print $1}'`)
echo ">>>>Getting LineNumArr is done"
for lineNum in "${lineNumArr[@]}"
do
############Replace logger
        sed -i "${lineNum} a printf('MSG_Log is show');" $fileName
        echo ">>>>Replace_logger is Done"
done
echo ">>>>for loop is closed"
exit

But it doesn't keep tabs on existing lines of code. For Example, I want to make my .cpp file like this,

#include<iostream>
int main(void){
  bool value=true;
....
     if(value){
        MSG_LOG("VALUE IS TRUE");
        printf('MSG_LOG is show');
      }
....

But when I actuate this shell script, the result is...

#include<iostream>
int main(void){
  bool value=true;
....
     if(value){
        MSG_LOG("VALUE IS TRUE");
printf('MSG_LOG is show');
      }
....

How can I add new code while preserving the tablines?

sed awk shell bash
2 Answers

You should add the same amount of withespace as the previous line when adding a new line.

You want something like this

sed -E 's/^(.*)(MSG_LOG\(.*\);)(.*)$/\1\2\3\n\1printf("MSG_LOG is show");/g'

If I understood correctly.

You don't have to invoke sed once per line as it loops over the entire file.

Also, you need double quotes in printf.

user_2364650

Using sed, you can duplicate the original line containing MSG_LOG and then replace the text, this will keep the tab spacing in place.

$ sed "/MSG_LOG/{p;s/[[:alpha:]].*/printf('MSG_LOG is show');/}" "$fileName"
user_163721090
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