#!/usr/bin/perl 
#my @files = ('data1.txt', 'data2.txt', 'data3.txt' );
my @files = `ls Data_files/*/Data.txt`;

foreach my $filename(@files){
    open FILE, $filename or die "Cannot open $filename for reading: $!\n";   
    ### Read Line by Line ###
    
    while($line=<FILE>){
	#read file line by line
    }
close(FILE);
}