Re: [tlug] Adding text to the beginning of a file

["Arwyn Hainsworth" <arwynh@example.com>]

On 16/03/07, Dave M G <martin@example.com> wrote:
> 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?

Sed is your friend:

sed '1,/^#--/ d' < file_with_data_to_replace > tmp_file
cat file_with_new_data tmp_file > end_result_file

The 1st line deletes everything from line 1, up until it finds a '#--'
at the start of the line.
The 2nd line just pastes the new data together with the old.

A nice tutorial on sed can be found here:
http://www.grymoire.com/Unix/Sed.html

Arwyn

PS Hello everyone! This is my first post to the list, yoroshiku.