You don't need to have your script "remember" all the lines in the current section (which I take it is the issue you want to solve), as long as you are judicious in your use of filehandles. My initial thought is along the following lines:

my $outfilename = "outfilename";

open INFILE, "$input_file" 
    or die "Can't open $input_file: $!\n";

while (<INFILE>) {
    if ( /section-end-marker/ ) {
       close OUTFILE;
       next;
    }
    if ( /section-start-marker/ ) {
        # generate the new $outfilename however
        open OUTFILE, "> $outfilename" or die"$!\n";
        next;
   }
    print OUTFILE;
}

[download]

That's very basic, but the idea is that you print to the currently open filehandle, unless you've found the start section marker, in which case you open the output file (to that filehandle), or the end section marker, in which case you close the curently open filehandle.

HTH

update OK, two people have failed to notice that the code is not to be used "as is": it is a skeleton upon which to build a functioning script. I left this implicit by putting comments where there would, in an actual script, be functioning code. I now make that implict warning explicit.

If not P, what? Q maybe?
"Sidney Morgenbesser"

In reply to Re: parsing of large files by arturo
in thread parsing of large files by Anonymous Monk

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.