Shell Programming and Scripting

file1     file2     file3
ABC              ABC
DEF    DEF         
GHI
           DER    DER

ABC                 ABC       
DEF       DEF                 
          DER       DER       
GHI

my $n=0;
my @tmp = glob("*.txt");
for(my $i=0;$i<=$#tmp;$i++){
  my $file = $tmp[$i];
  open FH,"<$file";
  while(<FH>){
    chomp;
    if(exists $hash{$_}){
     my @t = @{$hash{$_}->{VAL}};
     for(my $j=$#t+1;$j<=$i-1;$j++){
      push @{$hash{$_}->{VAL}},0;
     }
     push @{$hash{$_}->{VAL}},1;
    }
    else{
     $hash{$_}->{SEQ}=$n++;
     push @{$hash{$_}->{VAL}},1;
   }
}
  close FH;
}
foreach my $key (sort {$hash{$a}->{SEQ} <=> $hash{$b}->{SEQ}} keys %hash){
  my @tmp = @{$hash{$key}->{VAL}};
  my @t = map {my $tmp=($_ == 1)?$key:" ";$tmp;} @tmp;
  print join ",", @t;
  print "\n";
}