manual: misc. post-{build, image} scripts fixes

  directories, +.empty+ files and files ending with +~+ are excluded.

  _Among these first 3 methods, this one should be preferred_.

* In the Buildroot configuration, you can specify the path to a

  *post-build script*, that gets called 'after' Buildroot builds all the

  selected software, but 'before' the rootfs packages are

  assembled. The +BR2_ROOTFS_POST_BUILD_SCRIPT+ will allow you to

  specify the location of your post-build script. This option can be

* In the Buildroot configuration, you can specify the paths to one or

  more *post-build scripts*. These scripts are called in the given order,

  'after' Buildroot builds all the selected software, but 'before' the

  rootfs images are assembled. The +BR2_ROOTFS_POST_BUILD_SCRIPT+ allows

  you to specify the location of your post-build scripts. This option can be

  found in the +System configuration+ menu. The destination root

  filesystem folder is given as the first argument to this script,

  and this script can then be used to remove or modify any file in your

  filesystem folder is given as the first argument to these scripts,

  and these scripts can then be used to remove or modify any file in your

  target filesystem. You should, however, use this feature with care.

  Whenever you find that a certain package generates wrong or unneeded

  files, you should fix that package rather than work around it with a

  post-build cleanup script.

  files, you should fix that package rather than work around it with some

  post-build cleanup scripts.

  You may also use these variables in your post-build script:

    - +BUILDROOT_CONFIG+: the path to the Buildroot .config file

    - +HOST_DIR+, +STAGING_DIR+, +TARGET_DIR+: see

  installation. Note that this method is *not recommended*, as it

  duplicates the entire skeleton, which prevents from taking advantage

  of the fixes or improvements brought to the default Buildroot

  skeleton. The recommended method is to use the _post-build script_

  skeleton. The recommended method is to use the _post-build scripts_

  mechanism described in the previous item.

Note also that if you want to perform some specific actions *after*

all filesystem images have been created (for example to automatically

Note also that you can use the *post-image scripts*

if you want to perform some specific actions 'after' all

filesystem images have been created (for example to automatically

extract your root filesystem tarball in a location exported by your

NFS server, or to create a special firmware image that bundles your

root filesystem and kernel image, or any other custom action), you can

specify a space-separated list of scripts in the

+BR2_ROOTFS_POST_IMAGE_SCRIPT+ configuration option.

+BR2_ROOTFS_POST_IMAGE_SCRIPT+ configuration option. This option can be

found in the +System configuration+ menu as well.

Each of those scripts will be called with the path to the +images+

output directory as first and unique argument, and will be executed

with the main Buildroot source directory as the current

directory. Those scripts will be executed as the user that executes

Buildroot, which should normally not be the root user. Therefore, any

action requiring root permissions in one of these post-image script

action requiring root permissions in one of these _post-image scripts_

will require special handling (usage of fakeroot or sudo), which is

left to the script developer.