From this article:
http://alicebrawley.com/getting-r-to-notify-you-when-its-finished/
My general solution is to combine the R package mail, written by Lin
Himmelmann, and variations on an IFTTT (If This, Then That) recipe. I
use mail to send an email using functions in R, then IFTTT to notify
me immediately of that particular email.
Once you’ve installed mail, use the following functions to send
yourself an email when your code is completed.
#Have R email you when it's done running.
###Calculating - your wish is R's command.
library(mail)
#Send yourself an email - specify your preferred email address, subject, and message. The password is fixed at "rmail".
sendmail("xxxxx@xxxxx.com", subject="Notification from R", message="Conditions finished running!", password="rmail")
You can then use IFTT triggered by the email.
If you're sleeping next to your computer, consider also: Is there a way to make R beep/play a sound at the end of a script?