Rohan,
Make a CSV file Birthdays.csv with two columns:
primaryEmail,birthday
...
gam csv Birthdays.csv gam calendar "~primaryEmail" addevent summary "Birthday" recurrence "RRULE:FREQ=YEARLY" start allday "~birthday" end allday "~birthday" reminder <Minutes> <Method>
<Minutes> Number of minutes before the start of the event when the reminder should
trigger. Valid values are between 0 and 40320 (4 weeks in minutes).
<Method> The method used by this reminder. Possible values are:
- "
email" - Reminders are sent via email. - "
popup" - Reminders are sent via a UI popup.
Ross