jens-maus/yam

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 YAM - Yet Another Mailer
 Copyright (C) 1995-2000 by Marcel Beck <mbeck@yam.ch>
 Copyright (C) 2000-2022 YAM Open Source Team

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This is a short documentation on how to update the tz/zoneinfo sources
and data from https://www.iana.org/time-zones or https://github.com/eggert/tz
stored in the 'src/tools/tz' subdirectory of the YAM respository.

We are actually using the "git subtree" functionality to be able to easily
merge new updated tz/zoneinfo versions into our git repository. So please
refer to [1] and [2] for more information on git subtrees.

HowTo update the OpenSSL version in "src/tools/tz":
=================================================

1. To merge in a new tz/zoneinfo version execute the following git command
   within a working copy of the YAM repository:
   
   $ git subtree pull --prefix src/tools/tz --squash https://github.com/eggert/tz.git 2016d

   Note, that "2016d" can be replaced by any branch or tag of the tz/zoneinfo
   git repository at github.com (https://github.com/eggert/tz)

   After execution of the above subtree command git will try to merge in all
   changes between the currently utilized tz/zoneinfo version and the one specified
   and also adds the local changes applied due to our YAM changes.

2. In many cases the above command will result in merge conflicts which you
   need to resolve accordingly before you can commit the changes accordingly.

   Use the following command to display a list of files still in conflict:

   $ git diff --name-only --diff-filter=U

3. Go to the top-level of your working directory and execute the "scripts/mktzdata.sh"
   script which takes care to regenerate our binary zoneinfo files in the top-level
   resources directory.

   $ cd <top-level>
   $ scripts/mktzdata.sh

7. Review all changes with "git status" and make sure to commit everything
   properly.

   $ git status
   $ git commit -a -m "updated tz/zoneinfo to version 2016d"
   $ git push


HowTo generate a diff file of our YAM changes:
=============================================

1. Add a remote 'tz' branch to your git working copy and fetch all branches
   and tags accordingly:

   $ git remote add tz https://github.com/eggert/tz.git
   $ git fetch tz
   $ git fetch -t tz

2. Generate the diff from the top-level dir of your working copy.

   $ git diff 2016d master:tz
  
   to generate a diff to a remote branch use the following command instead:

   $ git diff master:tz remotes/tz/master

References:

[1] https://gist.github.com/kvnsmth/4688345
[2] https://medium.com/@v/git-subtrees-a-tutorial-6ff568381844#.q7ivzd39l