What drives me nuts is it returns "xx.txt" if "xx.txt" was passed to the "glob" even if "xx.txt" does not exist.

While that can be frustrating if it doesn't DWIM, I can think of a use for it.

foreach my $file_spec ( @ARGV )
{
  my @files = glob( $file_spec );
  foreach my $file ( @files ) 
  {
    if ( not(-e $file)
      and ( $file =~ /[.*]/ ) ) # change as appropriate
    {
      warn "Error: file $f doesn't exist,"
         . " or wildcard didn't match, " unless -e $file;
} } }
[download]

You might want to know which wildcard didn't match.