input.txt
 
 abhi)
       old_file="ak.csv"
        datefile="ak_nt_$curr_date.csv"
       cat /aksin/nil; cat /home/null
      
     case `kumar` in
       dbk)
           newwack="rac_client_$curr_date.ack"
           IN_DIR="class/5060"
       ;;
      src) 
          src_folder="class/5061
        ;;
    esac
       echo "$date_file"
   ;;

  bill)old_file="abh_cash.csv"
       date_file="ods_nt_cash_acc_$curr_date.csv"
       newwack="rac_cash_acc_$curr_date.ack"
       IN_DIR="xyx\5060"
   ;;

payu)
      old_file="ods_ven.csv"
     newfile="ods_nt_ven_$curr_date.csv"
     newwack="rac_vendor_$curr_date.ack"
     IN_DIR="ofc\5060"

    case para in
       bcc)
           newreck="client_$curr_simul.ack"
           IN_DIR="class/5062"
       ;;
      src1) 
          src_folder="class/5061
        ;;
    esac
     ;;
##########################  

##</code><code>##

 OUTPUT should be :

abhi: old_file="ak.csv"
abhi: datefile="ak_nt_$curr_date.csv"
abhi:dbk: newwack="rac_client_$curr_date.ack"
abhi:dbk: IN_DIR="class/5060"
abhi:src: src_folder="class/5061 

bill: old_file="abh_cash.csv"
bill: date_file="ods_nt_cash_acc_$curr_date.csv"
bill: newwack="rac_cash_acc_$curr_date.ack"
bill: IN_DIR="xyx\5060"
      
payu: old_file="ods_ven.csv"
payu: newfile="ods_nt_ven_$curr_date.csv"
payu: newwack="rac_vendor_$curr_date.ack"
payu: IN_DIR="gunda\5060"
payu:bcc: newreck="client_$curr_simul.ack"
payu:bcc: IN_DIR="class/5062"
payu:src1: src_folder="class/5061
        

##</code><code>##

 open (data, "<input.txt");
    while (<data>) {
   s/^\s+//g;                          #LTRIM
    if (/"(.*)"\)(.*)$/) {              #pattern match
        $parameter = $1;
        $var       = $2 . "\n";
    } else {
        $var = $_;
    }
  if (/case/../esac/){
     if (/"(.*)"\)(.*)$/) {
    $parameter ="$parameter:$1";
      $var       = $2 . "\n";
}
}
    if (/;;/) { print "\n"; next; }
  if($var=~/^\s*$/) {next;}      #if $var is empty or 1 or more than 1 whitespaces.
  elsif ($var!~/=/) {next;}      #ignore if $var does not consist "=" sign

else{
    print "$parameter: $var";
}
}
close data;