Sigh. My fault for posting untested code.
You are still missing the point about using Cwd. You don't need the chdir and you shouldn't rely on $ENV{PWD}. Here is a (tested) version showing what I mean.

use warnings;
use strict;

use Cwd;
my $curr_dir = cwd();

my $info_file = $curr_dir . '/../htdocs/info.txt';

open my $fh, '<', $info_file or die "Could not open file, $!";
while (my $line = <$fh>){
    # process text
}
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