As a programmer I found it strange that “interval” dont support a monthly parameter.
Days cant be used because the amount of days per month is not the same.
I do need to e-mail statistics & reboot the router on a monthly basis in order to charge my customers.
Cant think that I will be your only customer needing a monthly interval parameter.
I would run the script every day, and the first lines would parse the date. Save the stored month as a global variable, then every day when the script runs, get and parse the current date, then compare the current month to the stored month. If not equal, then it is a new month. Run the monthly update and set the stored month to the current month. Else exit.
I haven’t looked in the wiki. Maybe that would be a good idea.
ADD: If MT added the interval ‘M’ as month, then consider this schedule: