Somehow I have the feeling that the standard solutions, like te ones proposed here, don't really apply to your problem. I guess that you're actually trying to process in include-like tree, where some lines in a file point to other files, which you want to include as well... Am I right?

In that case, I would think somewhat in this direction: 

my @todo = glob('c:/*.inc');  # some kind of file
my %done;
undef $/;
while(@todo) {
    my $file = shift @todo;
    open FILE, "+<$file" or die "Can't open file $file: $!";
    $_ = <FILE>; # whole contents of file
    if(s/\bold\b/new/g) {
        # replace contents of file
        seek FILE, 0, 0;
        truncate FILE, 0;
        print FILE;
    }
    my($dir) = $file =~ m[(.*/)];
    while(/^#include (\S+);/mg) {
        push @todo, "$dir$1" unless $done{"$dir$1"}++;
    }
}

[download]
But I must admit that I haven't actually put this to a test, I only made sure it compiles. It's just to give you some ideas.

In reply to Re: changing inside a file by bart
in thread changing inside a file by amoura

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.