Find and replace in text files using AppleScript

Question

I am trying to write an applescript which will run via a launch agent. What the script needs to do is edit a user preference plist file so that default save locations are specific to that user. I am aware that this can be done by just setting "~/documents" as the location in the template plist. But Premier Pro for example also needs to write scratch files to a local drive. For simplicity I would like each user to have these put in a locations based on their username. This script will only need to run if the local profile has just been created from a template at first log on.

I have started by using some sample code found on this site and just making a simple test below. This test should edit a txt file and replace one word with another. This script is currently not working. When tested it opens up test.txt in TextEdit but does nothing more. No errors are displayed either.

Thank you in advance

John.

replaceText("replace this", "replace with this", "/Volumes/USB_Drive/test.txt")


on replaceText(search_string, replacement_text, this_document)
tell application "TextEdit"
    open this_document
    set AppleScript's text item delimiters to the search_string
    set this_text to the text of the front document as list
    set AppleScript's text item delimiters to the replacement_text
    set the text of the front document to (this_text as string)
    close this_document saving yes
end tell
end replaceText

Answer 1

Here an version that doesn't need text edit. It will read the file in utf-8 encoding, update it's contents and store that back into the file as utf-8 encoded text. The reason I use an try block around writing the file is that there will be an error if another application has the file open with read permission at the same time. The considering case block can be wrapped around the set ti to every text item of theContent if you want the search and replace case sensitive. There is no need for this to be active when you replace the string, only for finding it.

set stringToFind to "replace that"
set stringToReplace to "with this"
set theFile to choose file
set theContent to read theFile as «class utf8»
set {oldTID, AppleScript's text item delimiters} to {AppleScript's text item delimiters, stringToFind}
set ti to every text item of theContent
set AppleScript's text item delimiters to stringToReplace
set newContent to ti as string
set AppleScript's text item delimiters to oldTID
try
    set fd to open for access theFile with write permission
    set eof of fd to 0
    write newContent to fd as «class utf8»
    close access fd
on error
    close access theFile
end try