my @xml_files = glob( '*xml' );
#say for @xml_files;

my @bak_files = glob( '*bak' );
#say for @bak_files;

__END__

These would be the files: 
file_01.xml
file_02.xml
file_03.xml
file_01.xml.bak
file_02.xml.bak
file_03.xml.bak