(OSX) Capitalization using tr

Mac OSX Terminal/Unix question
I would like to capitalize the words at the beggining of sentences using the tr command, im not sure if this is possible, if not please tell me another way, I oly have TextEdit, no auto capitalization so just having a quick Unix way 'round it would be great.

Backup your file first. Then from terminal, vi the file

vi /users/yourid/novel.txt

Then type the following

:%s/[.!?]\_s\+\a/\U&\E/g
Hit enter

That should work for you. Then type :wq and press enter. Your file is edited and saved.

YAY! thankies!