Hi kcott,
OK, that got a bit of a chuckle as /3$/ was really intended as a non-solution to highlight the lack of information provided in the question...

Sorry, I misunderstood your write up. But I kind of see a solution in it, that was why I mentioned it.
Thinking if what the OP has is a file that contain say 

abcd_efgh-1.2.3
abcd_efgh-1.2.3-hjik-3.4.5.tar.gz

[download]
then simply doing this: 
while (<DATA>){
   print $_ if /3$/; 
}

[download]
prints abcd_efgh-1.2.3, and thanks to if /3$/; of course using ONLY these OP strings. It could be a different thing if there are other strings ending with "3".
All that been said on the assumption that, that was what was intended by the OP.

If you tell me, I'll forget.
If you show me, I'll remember.
if you involve me, I'll understand.
--- Author unknown to me

In reply to Re^3: Need help on regexp by 2teez
in thread Need help on regexp by siva.snimmaka

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.