Oooh! Ohhh! I always wanted to say this ...

You shoud use strict.

Also you might not want to use the variable names $a and $b because of how sort works.
Update with Example: 
Plankton@Chum_Bucket:~/perl/perlmonks> cat scritp.pl
#!/usr/local/bin/perl
use strict;
require "ex.txt";
my $bb = "blue\n";
&numbers ( $bb );
Plankton@Chum_Bucket:~/perl/perlmonks> cat ex.txt
sub numbers {
        my $v = shift;
        print "$v"
     }
 
1;

[download]

Plankton: 1% Evil, 99% Hot Gas.

In reply to Re: Passing Variables to External Subroutines (Perl/Tk) by Plankton
in thread Passing Variables to External Subroutines (Perl/Tk) by antioch

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.