live-build uses syslinux and some of its derivatives (depending on the image type) as bootloaders by default. They can be easily customized in a number of ways that range from providing a full theme to only modifying some files that allow you to, for example, change the boot timeout or simply add a personalized splash image.
In order to use a full theme, specify the --syslinux-theme option (see man lb_config). live-build will then retrieve the theme from the mirror and install it. You can also package your own theme or modify an already existing one and upload it to your local mirror.
Imagine that you want to build a Progress Linux client but you prefer to include the server's theme because you want to have the help menu. Then you would launch lb config as follows:
$ lb config --mode progress-linux --syslinux-theme progress-server
If you do not want to bother building a .deb, simply add your local configuration files for a default image to config/bootloaders/isolinux. Replacing isolinux for extlinux, pxelinux or syslinux depending on your use case.
There is also the possibility of making smaller changes. For instance, syslinux derivatives are configured by default with a timeout of 0 (zero) which means that they will pause indefinitely at their splash screen until you press a key.
To modify the boot timeout of a default iso-hybrid image just edit a default isolinux.cfg file specifying the timeout in units of seconds and add it to config/includes.binary/isolinux/
A modified isolinux.cfg to boot after five seconds would be similar to this:
include menu.cfg
default vesamenu.c32
prompt 0
timeout 50
An alternative way of achieving the same goal could be writing a hook and adding it to config/hooks/ Remember to add the .binary suffix to run in the binary stage. A proposed example:
#!/bin/sh
sed -i -e 's|timeout 0|timeout 50|' binary/isolinux/isolinux.cfg
Likewise, if you want to use a personalized splash.png image, add a picture of 640x480 pixels to config/includes.binary/isolinux/
When creating an ISO9660 binary image, you can use the following options to add various textual metadata for your image. This can help you easily identify the version or configuration of an image without booting it.