#!perl -w
use strict;

my %h;
my @files = ( 'FILE2.txt','FILE1.txt','FILE3.txt' );

foreach my $key ( @files )
{
     next unless -r $key;
     open( LOGFILE,"<$key" );
     while( <LOGFILE> )
     {
           $h{$key} .= $_; 
     }
     close LOGFILE;
}