Piping to mail and adding a subject line.
 

When I run a command or script and pipe it to mail, how do I add a subject line to the mail?

For example:

rsync -av /home/ /b/home | mail email@gmail.com

This will send the output, but without a subject line. Also, what if want to add some text in the body before the contents that are piped?

How about putting the message in a text file or maybe using the here doc would work....

mail -s "howdy" me@mydomain.com < message.txt

or

mail -s "howdy" me@mydomain.com << EOF
> this is a test
> EOF