[tlug] Adding text to the beginning of a file

[Dave M G <martin@example.com>]

TLUG,

I'm writing a bash shell which will write today's date and some other 
info at the top of a bunch of PHP files.

I believe that ordinarily, the command "cat" is used for this. However, 
unless I'm mistaken, "cat" will always add text to the beginning of the 
file.

What I'll need to do is to over write some text up to a particular point.

So, if at the top of my PHP file it says:

# File modified 2007 03 16
# by Dave M G
# --

Can I wipe out everything up to and including the "--" and then past in 
new text?

--
Dave M G
Ubuntu 6.10 Edgy Eft
Kernel 2.6.20-5-generic
Pentium D Dual Core Processor
PHP 5, MySQL 5, Apache 2