:B~ Customizing contents

1~customizing-contents Customizing contents

This chapter discusses fine-tuning customization of the live system contents
beyond merely choosing which packages to include. Includes allow you to add
or replace arbitrary files in your live system image, hooks allow you to
execute arbitrary commands at different stages of the build and at boot
time, and preseeding allows you to configure packages when they are
installed by supplying answers to debconf questions.

2~includes Includes

While ideally a live system would include files entirely provided by
unmodified packages, it is sometimes convenient to provide or modify some
content by means of files. Using includes, it is possible to add (or
replace) arbitrary files in your live system image. live-build provides two
mechanisms for using them:

_* Chroot local includes: These allow you to add or replace files to the
chroot/Live filesystem. Please see {Live/chroot local
includes}#live-chroot-local-includes for more information.

_* Binary local includes: These allow you to add or replace files in the
binary image. Please see {Binary local includes}#binary-local-includes for
more information.

Please see {Terms}#terms for more information about the distinction between
the "Live" and "binary" images.

3~live-chroot-local-includes Live/chroot local includes

Chroot local includes can be used to add or replace files in the chroot/Live
filesystem so that they may be used in the Live system. A typical use is to
populate the skeleton user directory (#{/etc/skel}#) used by the Live system
to create the live user's home directory. Another is to supply configuration
files that can be simply added or replaced in the image without processing;
see {Chroot local hooks}#chroot-local-hooks if processing is needed.

To include files, simply add them to your #{config/includes.chroot}#
directory. This directory corresponds to the root directory #{/}# of the
live system. For example, to add a file #{/var/www/index.html}# in the live
system, use:

code{

 $ mkdir -p config/includes.chroot/var/www
 $ cp /path/to/my/index.html config/includes.chroot/var/www

}code

Your configuration will then have the following layout:

code{

 -- config
    [...]
     |-- includes.chroot
     |   `-- var
     |       `-- www
     |           `-- index.html
    [...]

}code

Chroot local includes are installed after package installation so that files
installed by packages are overwritten.

3~binary-local-includes Binary local includes

To include material such as documentation or videos on the medium filesystem
so that it is accessible immediately upon insertion of the medium without
booting the Live system, you can use binary local includes. This works in a
similar fashion to chroot local includes. For example, suppose the files
#{~/video_demo.*}# are demo videos of the live system described by and
linked to by an HTML index page. Simply copy the material to
#{config/includes.binary/}# as follows:

code{

 $ cp ~/video_demo.* config/includes.binary/

}code

These files will now appear in the root directory of the live medium.

2~hooks Hooks

Hooks allow commands to be run in the chroot and binary stages of the build
in order to customize the image. Depending on whether you are building a
live image or a regular system image you have to place your hooks in
#{config/hooks/live}# or #{config/hooks/normal}# respectively. These are
frequently referred to as local hooks because they are executed inside the
build environment.

There are also boot-time hooks that allow you to run commands once the image
has already been built, during the boot process.

3~chroot-local-hooks Chroot local hooks

To run commands in the chroot stage, create a hook script with a
#{.hook.chroot}# suffix containing the commands either in the
#{config/hooks/live}# or #{config/hooks/normal}# directories. The hook will
run in the chroot after the rest of your chroot configuration has been
applied, so remember to ensure your configuration includes all packages and
files your hook needs in order to run. See the example chroot hook scripts
for various common chroot customization tasks provided in
#{/usr/share/doc/live-build/examples/hooks}# which you can copy or symlink
to use them in your own configuration.

3~ Binary local hooks

To run commands in the binary stage, create a hook script with a
#{.hook.binary}# suffix containing the commands either in the
#{config/hooks/live}# or #{config/hooks/normal}# directories. The hook will
run after all other binary commands are run, but before binary_checksums,
the very last binary command. The commands in your hook do not run in the
chroot, so take care not to modify any files outside of the build tree, or
you may damage your build system! See the example binary hook scripts for
various common binary customization tasks provided in
#{/usr/share/doc/live-build/examples/hooks}# which you can copy or symlink
to use them in your own configuration.

3~boot-time-hooks Boot-time hooks

To execute commands at boot time, you can supply live-config hooks as
explained in the "Customization" section of its man page. Examine
live-config's own hooks provided in #{/lib/live/config/}#, noting the
sequence numbers. Then provide your own hook prefixed with an appropriate
sequence number, either as a chroot local include in
#{config/includes.chroot/lib/live/config/}#, or as a custom package as
discussed in {Installing modified or third-party
packages}#installing-modified-or-third-party-packages.

2~ Preseeding Debconf questions

Files in the #{config/preseed/}# directory suffixed with #{.cfg}# followed
by the stage (#{.chroot}# or #{.binary}#) are considered to be debconf
preseed files and are installed by live-build using
#{debconf-set-selections}# during the corresponding stage.

For more information about debconf, please see #{debconf(7)}# in the
/{debconf}/ package.
