Without knowing what your HTML file contains, I cannot reproduce your problem. Please replace the reading of the HTML file into $html by hardcoding the value of $html. For example:

my $html = <<'HTML';
<html>
<body>
<!--#include file="somefolder/cc.html" -->
</body>
</html>
HTML

[download]

See also SSCCE for an incredibly effective technique on how to debug things and provide information for others so that they can diagnose your situation and suggest approaches.

When I modify your script to be self-contained, it does just what I expect: 

use strict;
use warnings;

my $htmlfile ='/var/www/html/xx/xxx/1204.html';
my $html = <<'HTML';
<html>
<body>
<!--#include file="somefolder/cc.html" -->
</body>
</html>
HTML

#path of the included file
my $includepath="/var/www/html/xx/xxx/";

if ($html =~ s{#include file="([^"]+)"}{&add_template($1)}gei)
    {
        print "the file has include file";
        print $html;
    }
    else
    {
        print "doesn't have";
        print $html;
    }



sub add_template {
        my $file = shift;
        print "$file\n";
        my $display_file="$includepath$file";
        print $display_file, "\n";
         if (-e $display_file){
             #print "$display_file";
             return read_file($display_file);

            } else {
            # warn "$display_file not found";
            return "<!-- $display_file not found to include -->";
                         }
}

[download]

You will note that I changed the error message so that it outputs the value of $display_file. This is highly important as in your case, there may be a typo or a permissions error or something.

In reply to Re^9: displaying html file in the browser using perl by Corion
in thread displaying html file in the browser using perl by tsdesai

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