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diff --git a/docs/example_hook b/docs/example_hook new file mode 100644 index 0000000..a0d015a --- /dev/null +++ b/docs/example_hook @@ -0,0 +1,114 @@ +#!/bin/sh + +# +# This is an example hook script. It will be run by 'mkinitramfs' +# when it creates the image. It's job is to decide which files to +# install, then install them into the staging area, where the +# initramfs is being created. This happens when a new 'linux-image' +# package is installed, or when the administrator runs 'mkinitramfs' +# by hand to update an initramfs image. +# +# TODO: What about the case where you install something that should be +# added to the initramfs, but the linux-image it relates to has +# already been installed previously? Does this happen often +# enough that it needs to be handled? How can it be handled? +# +# * Think about the 'usplash'. The initramfs will need to be +# updated if a theme change or update is desired. Maybe it +# should not be totally automatic, but offered on upgrade +# predicated on a user response to a debconf question? That +# issue needs to be explored and a solution specified. +# +# * Do not assume that any needed subdirectories have been created +# yet, but don't bail out if they are already there. +# +# * All of the standard system tools are available, of course, since +# this hook is running in the real system, not the initramfs. +# +# * TODO: ... ? Anything else to tell them in this bullet-list? +# + +# +# The environment contains at least: +# +# CONFDIR -- usually /etc/mkinitramfs, can be set on mkinitramfs +# command line. +# +# DESTDIR -- The staging directory where we are building the image. +# +# TODO: Decide what environment variables are meaningful and defined +# in this context, then document them as part of the interface. +# +# TODO: May need a version_compare function for comparison of VERSION? + + +# +# List the soft prerequisites here. This is a space separated list of +# names, of scripts that are in the same directory as this one, that +# must be run before this one can be. +# +PREREQ="" + +prereqs() +{ + echo "$PREREQ" +} + +case $1 in +# get pre-requisites +prereqs) + prereqs + exit 0 + ;; +esac + + +# You can do anything you need to from here on. +# + +# Source the optional 'hook-functions' scriptlet, if you need the +# functions defined within it. Read it to see what is available to +# you. It contains functions for copying dynamically linked program +# binaries, and kernel modules into the DESTDIR. +# +. /usr/share/initramfs-tools/hook-functions + + +# If this hook script is a conffile (and thus stored in +# /etc/mkinitramfs/hooks), it must take care to do the right thing +# when the package containing it is removed but not purged. There of +# course may be other reasons to have custom logic deciding what to +# install. The version variable may be useful for this. +# +if [ -x /usr/bin/myprog ]; then + copy_exec /usr/bin/myprog usr/bin +fi + +# To accompany this, there should usually be a script for inside the +# initramfs named something like: +# +# "/etc/mkinitramfs/local-premount/myprog" +# +# ... and it should do what is necessary to have 'myprog' get run +# inside the early runtime environment. + +# Handle an error: +# +if [ -n "$an_error_occured" ]; +then + # + # TODO: Do we need 'warn()', 'error()', and/or 'fatal()' for this? + # + echo "An error occured in $0: $an_error_occured" >&2 + exit 1 + # + # TODO: Decide if different error codes are meaningful, what they + # mean, and what the semantics of them are wrt 'mkinitramfs' + # pass or fail. Consider naming the error values with + # mnemonic symbols rather than magic numbers. They may or + # may not be the same set of errors as the set for + # in-initramfs scripts. + # +fi + +exit 0 |