How to use a function inside a shell

[KKeshari]

Dear All,

I am very new to shell script, and my requirement is --

1. open the apache access log, use "cut" and "grep" to find the numbers.
2.put the result in a file
3.then compare the same result with day before result
4. send the result via e-mail.

so how can i do that , using some functions..

[Schmidt]

Advanced Bash-Scripting Guide

You're welcome