#!/usr/bin/perl -w

use strict;

while ( <DATA> ) {


        s/ angle brackets between element pairs / instead make square 
+bracketed /


        print $_ . "\n";


}

__DATA__

<sometag> my data here </sometag>
<anothertag> further text </anothertag>
<furthertag> not good as contains <this> in angle brackets </furtherta
+g>
<byetag> another possibility is <more> <than> one <angle pairs> in her
+e </byetag>
[download]

<sometag> my data here </sometag>
<anothertag> further text </anothertag>
<furthertag> not good as contains [this] in angle brackets </furtherta
+g>
<byetag> another possibility is [more] [than] one [angle pairs] in her
+e </byetag>
[download]

That looks like XML. I'd seriously consider using XML::Twig!

If you need some help show us some representative data and what you actually want to extract

---

DWIM is Perl's answer to Gödel

It is of a fashion - impossibly malformed XML. The data now given above ( and specified output ) is now fully representative, this tool is effectivley a parser to take some poor output, to poor, but well-formed XML. Although Im keen to continue with this approach, is the solution on a differant approach ?

This violates your "no code" premise, but if your tags are all on one line, this seems reasonably robust and should be fairly efficient.

#! perl -sw
use strict;

while( <DATA> ) {
    s[^(<([^>]+?)>)(.*)(</\2>)]{
        (my $x = $3) =~ tr[<>][[]];
        "$1$x$4";
    }e;
    print;
}


__DATA__
<sometag> my data here </sometag>
<anothertag> further text </anothertag>
<furthertag> not good as contains <this> in angle brackets </furtherta
+g>
<byetag> another possibility is <more> <than> one <angle pairs> in her
+e </byetag>
<a tag with spaces> and content containing a false </a tag with spaces
+> and a real </a tag with spaces>
[download]

Produces

C:\Perl\test>junk2
<sometag> my data here </sometag>
<anothertag> further text </anothertag>
<furthertag> not good as contains [this] in angle brackets </furtherta
+g>
<byetag> another possibility is [more] [than] one [angle pairs] in her
+e </byetag>
<a tag with spaces> and content containing a false [/a tag with spaces
+] and a real </a tag with spaces>
[download]

Of course, it doesn't attempt to deal with attributes, or multi-line elements or nested tags or any of that good stuff.

---

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal?

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

Thanks - Considering all the responses, I think attempting to do this +without+ a small amount of code, ie an a single 'replace' expression is not the best approach. Thanks for this solution.