Thanks for the general tips, I apologise for the delay in replying - I have been trying to synthesise the salient parts or the script

In fact I have isolated what is causing the problem, but I'm not sure why or how I should change things to do what I want.
The background is that several scripts are accessed by a single user by way of a 'work page', containing buttons for those scripts.
When a script is finished with it uses wslib ( soon to be WSLib(!! :) ) to create a new work page, using html::template (not shown to keep the example simple.
In this particular instance the script edits the text file $data_reg called up in sub workspace, and renames it. If I comment out the rename line, sub workspace prints out the whole file, if I leave it in it only prints three quarters of it!! How should I deal with this?

sub edit {
 
 my $newline = join "\t", ($count_in,$current_time_in,$user_in,$passwo
+rd_in,$email_in,$web_in,$agencyname_in,$business_in,$country_code_in,
+$mobile_no_in,$sec_email_in,$skip);

 open FH, "$data_reg" or die "Can't open data_reg file for reading: $!
+";    
 flock (FH, 1) or die "Can't lock data_reg file for reading";
 my @alldata = <FH>;
 close FH;

 open FILE, '>', "$data_reg.tmp" or die "Can't open data_reg file for 
+reading: $!";    
 flock (FILE, 2) or die "Can't lock data_reg.tmp file for writing";
 
  foreach (@alldata) {
    chomp;
    ($count,$current_time,$username,$password,$email,$web,$agencyname,
+$business,$country_code,$mobile_no,$sec_email,$skip) = split /\t/;
    if ($user_in eq $username) {
      print FILE "$newline\n";
    } else {
      print FILE "$_\n";
    }
  }
#  rename ("$data_reg.tmp", "$data_reg") or die "Can't rename file: $!
+"; ##only prints properly if commented out!
  &workspace(@exp);
  
  
}
[download]