Rename with last day of month when source only contains year-month

Hello there,

I’m creating smart rules to automatically rename and file my monthly statements and most of them have the complete date information, but there is one where I only have the month and year, and I’d like to rename it to has the last day of that month.

My input is a file named Brokerage Statement - XXXX1234 - 202111 where the last digits are the date with the format yyyymm, I create the following Smart Rule to detect the date but it gives me the first day of the month.

Is there a way to convert it to the last day of the month before I rename it?

I tried using the Oldest Document Date placeholder but it gives me a totally unexpected result: with input = 202111, results in 2021-01-20.

My goto is Applescript

Or this other scripting language. I’d use the first day of the next month and then subtract one day. That should work with leap years too, but one has to take care of December/January.

1 Like

I thought I’d have to go the scripting route, is there a way to pass parameters to the script? In this I’d like to send the script the regex groups that Scan Name found. The actions would be something like this:

  1. Scan Name, Date
  2. Execute Script to rename the file - with the output of scan name as input for the script
  3. Move

The record is passed to the script
See the skeleton script below

on performSmartRule(theRecords)
	tell application id "DNtp"
		repeat with theRecord in theRecords
                                           <<< insert code
		end repeat
	end tell
end performSmartRule

I’d like to rename it to has the last day of that month

Here’s example code to get the last day of the month and rename the record

			set theName to name of theRecord
			set theName to theName & my LastDay(texts -6 thru -1 of theName)
			set name of theRecord to theName

on LastDay(theDate)
	set theyyyy to characters 1 thru 4 of theDate as string
	set themm to characters 5 thru 6 of theDate as string
	-- Convert to the first day of the following month
	-- Then get the previous day
	set NewDate to current date
	set year of NewDate to theyyyy
	set day of NewDate to 1
	set month of NewDate to (themm as integer) + 1
	set NewDate to NewDate - (1 * days)
	return day of NewDate
end LastDay

Thank you! While my brain finds AppleScript only workable when I have it fully ready to use and only need a few tweaks your example made me try to do it in JavaScript and I got there:

function performsmartrule(records) {
	records.forEach (record => {
		const originalName = record.nameWithoutExtension()
		const rawDate = originalName.match(/test.+(\d{4})(\d{2})/)
		const year = rawDate[1]
		const month = rawDate[2]
		// JS month is zero-indexed, to get last day of a month we pass 0 of the next month
		const lastDay = new Date(year, month, 0).getDate()
		const documentDate = [year, month, lastDay].join("-")
		const newName =, documentDate + " - Test") = newName

It even works for leap year. Given the file test something 202002.txt it gets renamed to 2020-02-29 - Test.txt.


I’ve never seen that before. :+1: