[oe] changing system configuration in a customized image

[Stefan Buschmann]

Hi all!

I'm using a customized image of SHR that includes some additional 
packages I like to have installed automatically as well as a package 
that should include the changes to the system configuration that I need. 
It would just be nice to have this done automatically rather than having 
to tweak the system by hand every time I build and install a new image 
on the device.

So e.g. I would like to change configuration files and execute some 
commands:
- Add a system user
- Install customized version of '/etc/samba/smb.conf'
- Set samba password via 'smbpasswd'

I think I can't simply run those commands via install or staging task, 
because I wouldn't be able to run something like 'smbpasswd' there. So I 
figure the way to go would be to add a configuration script which runs 
only on the first system start, that can modify the configuration files 
and run the necessary commands.

So is this the right approach? How can I add such a script? I tried to 
find out by looking into e.g. the recipe for 'alsa' but didn't find a 
clue there. Also I'm making my way through the OpenEmbedded User Manual 
but couldn't find it there either.

Thanks,

Stefan