$ perl -MO=Deparse junk
print "Before: @x$/";
use File::Glob ();
while (defined(my $ele = glob(join $", @x))) {
    do {
        next unless $ele;
        print "$ele becomes ";
        $ele =~ s/^(.)/x$1/;
        print $ele . $/
    };
}
print "$/After: @x";
__DATA__
junk syntax OK