#!usr/bin/perl
use strict;

open FH, "/home/test1/hello.csv" or die;
my @array,@array1;

#----------I'm pushing all abc's and def's data into respective arrays---------------------------

while(<FH>)
{
  if ($_=~/^abc/)
    { 
       push(@array,$_);
     
              }
  elsif($_=~/^def/)
    { 
       push(@array1,$_);
     
              }

           }
#----------I'm writing only one for loop for abc, it will be same for def too. ------------------------------

my @hello;
foreach my $i(0..$#array-1)
{
#-------below code: it splits the second abc and and so on. i.e., strips second abc from the digits.-------------------

@hello=split  /^\w+\,/,$array[$i+1];


foreach my $j(0..$#hello)
{
#--------below code:this is for replacing \n of first abc,2,3,4,5,6 with a comma ( ex: abc,2,3,4,5,6, ) 

$array[$i]=~s/\n/,/g;

#--------------below code:here it concatenates the data ( data should look like: 2,3,4,5,6,7,5,2,1,6,2,3,8,2,1,3,1,4 )----------

abc,$array[$i]=$array[$i].$hello[$j];
print $array[$i],"\n";

}
}
# In my above code, the data is concatenated as follows:
abc,2,3,4,5,6 
,7,5,2,1,6,2,3
,8,2,1,3,1,4

#But expected output is :
abc,2,3,4,5,6,7,5,2,1,6,2,3,8,2,1,3,1,4