i took your advice and did the modification and writing in a new file and then renamed it to the original  filename..
  i first named the new files as mod_$filename. Then globbed the directory for a list of all mod_* files..

  @rename_list=<mod_*>;

Then i did a loop to rename all mod_filename as filename.
  foreach(@rename_list)
 {
    $filename=substr($_,index($_,'mod_')+4);
    rename($_,$filename);
  }

 but something weird happens.. all the files get renamed except for the last file on the rename list.
  i thought maybe som prob with the file and so i deleted that particular file from the directory. But still the last of the remaining files doesn't get renamed.
   Any idea why this is so...?



I can't see anything odd from a quick look through that.   Have you printed out the @rename list completely so see if the problem is in the globbing or in the loop?   That's the next thing I would do.

---