// this code taken from http://bbs.applescript.net/viewtopic.php?id=20330

do shell script "grep string /Users/username/Desktop/QSPresetQSFileTagsPlugIn.qsindex | awk {'print $1'}"

set theTags to result

set newText to switchText of theTags from "<string>qs.tag.file</string>" to ""

to switchText of currentText from SearchString to ReplaceString -- the handler
   
   set storedDelimiters to AppleScript's text item delimiters
   -- this simply stores the current value of AppleScript's AppleScript's text item delimiters
   -- so they can be restored later (thus helping to avoid potential problems elsewhere).
   -- Remember, we always set them back to what they were.
   
   set AppleScript's text item delimiters to SearchString
   -- AppleScript's AppleScript's text item delimiters are now set to "Purple"
   
   set currentText to currentText's text items -- note we have changed currentText's value
   -- create a list of text items from the original text, separated at the points where the
   -- current text item delimiter ("Purple") appeared.
   --> {"What, ", " Shoes?"} - Note that the spaces and punctuation are retained.
   
   set AppleScript's text item delimiters to ReplaceString
   -- AppleScript's AppleScript's text item delimiters are now set to "Green"
   
   set currentText to currentText as Unicode text
   -- coerce the list {"What, ", " Shoes?"} to Unicode text. This operation will also
   -- insert the current value of AppleScript's AppleScript's text item delimiters ("Green")
   -- between each of the listed items
   
   --> "What, Green Shoes?"
   
   set AppleScript's text item delimiters to storedDelimiters
   -- restore the value of AppleScript's AppleScript's text item delimiters
   -- to whatever they were on entering the subroutine. Remember that a call to this
   -- might have been made from within a section of script that had the TIDs set to
   -- something else. Hand the result back with the TIDs as they were.
   
   currentText
   -- return the now modified text (and restored TIDs) -- "What, Green Shoes?"
   
   
   set this_text to currentText
   
   set new_text to ""
   
   --Loop through paragraphs of old text
   repeat with myPara in paragraphs of this_text
       --Check for paragraph’s contents in new text
       --If not there add new text to end of new text
       if new_text does not contain myPara then set new_text to new_text & myPara & return
   end repeat
   --Remove final return
   set new_text to (characters 1 thru -2 of new_text) as text
   
end switchText -- the end of the handler.