i have two separate scripts that work nicely to curl and generate two files.. one html and one txt so a total of four.

When the script starts up i want it to:
call and run shellscripta
call and run shellscriptb
sleep for about 40 seconds
again run shellscripta
again run shellscriptb
check and make sure both txta and txtb exist then..
check for any differences..
if they are the same than continue loop/sleep
if the two text files contain different data
email user@somewhere.com with the data of both files then continue loop
--loop stops when i run 'xcommand stop'


There are two parts of this that's difficult for me.. one is creating a loop that starts and stops when i tell it.. the other is the portion that checks for differences then emails.. the script has to 'head -n4' both text files to see if there are any differences.. if there are i need it to 'mail' me both parts of the text files 'head -n5' (5th line containing the date so i know what's oldvsnew).. i hope i'm making some sense but any help would be great