Shell Programming and Scripting

Perfect. Thanks guys. I will build the script to handle other situation too.

The solution you get here can only be as good as your description of the problem.

You say you actual CSV file has 21 columns (fields?) you the sample data you supply only has 4 line of 7 fields.

Yoda states his solution is based on the sample data, probably due to this confusion.
RavinderSingh13's solution will only work if your CSV files always starts with the digit "1" and/or contains the string "ABC".

If these are working for you all is good but if you need something that works for your actual data you might need to provide a better description of what is needed.

For example:
- how many fields are in the actual data
- are records split over more than 2 lines
- do you always need a space inserted when lines are joined (like what happens when lines 2 and 3 are joined from you sample data)