Create a duplicate record based on a condition

Question

I need to write a shell script where I have to create a duplicate record based on a condition and then change the value in a column of the new row which will be created.

I am trying to create a duplicate record based on a condition and then replace on column in the duplicate row.

Example:

Input will be

Col1,Col2,Col3,Col4,COl5

1234,abcd,abcd,wxyz,USD
2345,abcd,abcd,wxyz,USD
3456,abcd,abcd,wxyz,EUR

If the last column ie; col5 is EUR, then one more row should be created with change in column value.

Output should be

Col1,Col2,Col3,Col4,Col5

1234,abcd,abcd,wxyz,USD
2345,abcd,abcd,wxyz,USD
3456,abcd,abcd,wxyz,EUR
3456,abcd,abcd,wxyz,AUD

Answer 1

Here are a couple of ways:

• awk

  awk -F, '{print; if($NF=="EUR"){$NF="AUD"; OFS=",";print}}' file
  

  That is checking the last field ($NR) to check another field, change $NR to $N, where N is the number you want to check (e.g $3 for the 5th field).

• Perl

  perl -pe '$_.= "$1AUD\n" if /(.*)EUR$/' file 
  

  This one uses a lot of Perl shorthand that is kind of harder to explain. You can write the same thing like this:

  perl -e 'while(<>){if(/(.*)EUR$/){print "$_","$1AUD\n"} else {print "$_"}}' 
  

for each line of the input file

Answer 2

using sed:

 sed -e 's|^\(.*\),EUR$|\1,EUR\r\1,AUD|'

Answer 3

A Perl alternative

perl -ne 'print;print if s/EUR\Z/AUD/' your_file

If you want to make the modifications to the file in place, just add the -i switch:

perl -ni -e 'print;print if s/EUR\Z/AUD/' your_file