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

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?

CodePudding user response：

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.

CodePudding user response：

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"