[erlang-questions] Reltool anyone?

Tuncer Ayaz <>
Sun Aug 24 19:04:28 CEST 2014


On Sat, Aug 23, 2014 at 8:51 PM, Joe Armstrong wrote:
> I think it might be a better idea if you explained how booting
> erlang works
>
> *exactly* what happens when you do "erl -boot XYZ.boot"
>

[...]

> The *reason* they are written as binaries and use binary_to_term to
> "see" them is because when the system is loaded the code to parse
> erlang terms has not yet been loaded - this code gets loaded by the
> boot loader a little bit later.
>
> The stuff in systools and reltool basically takes the pain out of
> manipulating the boot files. Once you've understood the bootfile
> structure the rest is easy.
>
> This is actually described in
>
> http://www[...]/doc-4.9.1/doc/system_principles/system_principles.html

If you're looking for the same info in a current release, see:

http://www.erlang.org/doc/system_principles/system_principles.html

$ erl -man script
or load http://www.erlang.org/doc/man/script.html

$ erl -man systools
or load http://www.erlang.org/doc/man/systools.html

$ erl -man init
or load http://www.erlang.org/doc/man/init.html

> But very few people seem to notice this - it might be an idea to
> emphasis how easy the start phases are. Once you hide what's really
> going on with tools you can get into deep waters if the tools stop
> working and you don't really understand whats happening under the
> covers ...
>
> Anybody who really wants to understand how the system starts should
> write some simple bootscripts by-hand and see what happens when they
> are run :-)



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