system ('grep -l "DATAmessage.*3\.0" *.xml > 3.0_files_arraydata.txt');

##</code><code>##


open my $FH, '>', '3.0_files_arraydata.txt'
    or die "Cannot open '3.0_files_arraydata.txt' because: $!";

{   local @ARGV = <*.xml>
        or die "Cannot find any '*.xml' files\n";

    while ( <> ) {
        if ( /DATAmessage.*3\.0/ ) {
            print $FH "$ARGV\n";
            close ARGV;
            }
        }
    }


##</code><code>##

system ("mv temp_3.0_files_onixarraydata.txt 3.0_files_arraydata.txt");

##</code><code>##

rename 'temp_3.0_files_onixarraydata.txt', '3.0_files_arraydata.txt'
    or die "Cannot move 'temp_3.0_files_onixarraydata.txt' because: $!";


##</code><code>##

system ("cat *files_arraydata.txt > data2.txt");

##</code><code>##

open my $FH, '>', 'data2.txt'
    or die "Cannot open 'data2.txt' because: $!";

{   local @ARGV = <*files_arraydata.txt>
        or die "Cannot find any '*files_arraydata.txt' files\n";

    print $FH $_ while <>;
    }


##</code><code>##

system ("rm data2.txt");

##</code><code>##

unlink 'data2.txt'
    or die "Cannot delete 'data2.txt' because: $!";


##</code><code>##

system ("sort -u data2.txt > data.txt");

##</code><code>##

open my $IN,  '<', 'data2.txt'
    or die "Cannot open 'data2.txt' because: $!";

open my $OUT, '>', 'data.txt'
    or die "Cannot open 'data.txt' because: $!";

{   my %unique;

    print $OUT sort grep { ! $unique{ $_ }++ } <$IN>;
    }