[Koha] placing text into 520 tag. Help plz.!

hello, i want to embed this code in 520 tag so that it places text file into 520 (abstract) tag before saving the record .... the following php code accepts a pdf file path, converts it 2 text and place it into the text area. $file=$_POST['file']; exec ("pdftotext $file '/var/www/testFile.txt'"); exec ("tr -d '\012' </var/www/testFile.txt> /var/www/tf.txt"); $myFile = "/var/www/tf.txt"; $fh = fopen($myFile, 'r'); $theData = fread($fh, 10000000); fclose($fh); echo '<textarea name="stuff" cols="60" rows="10">'; echo stripslashes($theData); echo '</textarea><br>'; want to place this text into the abstract field(520 tag). plz help me doing this. Thank u :)