Add one to number in text document

I want a terminal command that will edit a text file by adding 1 to the number in the text.

The entire contents of the text file is just a number.

I'm running the command through appleScr开发者_开发知识库ipt's do shell script command.

Quick and dirty:

do shell script "echo $(( $(<FoO) + 1 )) >FoO"