open(my $fh_in, '<', $qualified_name)
   or die("Unable to open file \"$qualified_name\" to split: $!\n");

##</code><code>##

>dir /b *.log
foo.log

>type foo.log
1
2
3
4
5
6
7
8
9
10

>perl !.pl foo.log

>dir /b *.log
foo-0.log
foo-1.log
foo-2.log
foo-3.log
foo.log

>for %q in (foo-*.log) do type %q

>type foo-0.log
1
2
3

>type foo-1.log
4
5
6

>type foo-2.log
7
8
9

>type foo-3.log
10