my @files = <data/j*.?.txt>;

##</code><code>##

#!/usr/bin/env perl
use strict;
use warnings;

my @files = <data/j*.*.txt>;
if (@ARGV) {
    @files = map { <data/$_> } @ARGV;
}   
        
print "Using @files";

##</code><code>##

$ ./gt.pl 
Found data/j.a.txt data/j.foo.txt data/j.xyz.txt
$ ./gt.pl 'j*.?.txt'
Using j*.?.txt instead
Found data/j.a.txt