In addition to what has been said: the "(" and ")" characters create so-called "groups", and the first group is assigned to $1, the second to $2, and so on. See perlre, especially the section on Capture groups.

For more "basic" information you might want to look into perlintro (which is part of perl's "official" doc), or http://learn.perl.org or http://perl-begin.org

BTW if you have perl on your computer, you can get at perl's documentation via perldoc, e.g. 
perldoc perlintro

[download]

In reply to Re^4: To print the file in spool with the new format of input file also by soonix
in thread To print the file in spool with the new format of input file also by skr302

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.