I was advised to come here: http://www.linuxquestions.org/questions/showthread.php?p=5271797#post5271797
This is the code: 

#!/usr/bin/perl

use warnings;

for ($x = 1; $x < 10; $x++) {

if ($_ =~ /^\d/) {$y = $y + 1;}    # if the line does start with a num
+ber, ignore it. 
if ($_ != /^\d/) {print $y.$x;}    # if the line doesn't start with nu
+mber then print numbers.
}

[download]
After running it:  perl counting.pl python.txt I get the following error:
Use of uninitialized value $_ in pattern match (m//) at counting.pl line 7.
Use of uninitialized value $_ in pattern match (m//) at counting.pl line 8.
Use of uninitialized value $_ in numeric ne (!=) at counting.pl line 8.
etc.

Purpose of the program is to line numbers according to chapter:
1.
1.1
1.2
2.
2.1
2.2

In reply to numbering lines problem by WisDomSeeKer34

Title:
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