Shell – How to Add Headers to a CSV File with Existing Headers Using Unix, AWK, SED, and SH

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My requirement it to add the new headers to an existing CSV file which already has some headers in the fist line. I need to add the new headers at the end of the existing headers. The value of the new headers will be empty; I just need to create the header.

For e.g. below is my CSV file

Cust_Name,Cust_ADD
A1,CBD
A2,CBE
A3,CBE

I need to add headers "salary,age" at the end of the CSV file.

I tried this code

sed -i "1s|\$|,$new_headers|" input.csv

It is giving me output like below

Cust_Name,Cust_ADD
,Salary,age
A1,CBD
A2,CBE
A3,CBE

The new headers are appearing on the second line.

Expected Output

Cust_Name,Cust_ADD,salary,age
A1,CBD,,
A2,CBE,,
A3,CBE,,

Best Answer

With any awk

% awk '{NR == 1 ? $0=$0",salary,age" : $0=$0",,"}1' file.csv
Cust_Name,Cust_ADD,salary,age
A1,CBD,,
A2,CBE,,
A3,CBE,,

Data

% cat file.csv
Cust_Name,Cust_ADD
A1,CBD
A2,CBE
A3,CBE
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