Release and Application Config

Eranga Udesh <>
Mon Oct 3 14:09:25 CEST 2005

Hi Chandru,

Thanks for the advice. Crystal clear.

- Eranga

-----Original Message-----
From: chandru [mailto:] 
Sent: Monday, October 03, 2005 3:26 PM
To: Eranga Udesh
Cc: Erlang Questions
Subject: Re: Release and Application Config


On 03/10/05, Eranga Udesh <> wrote:
> Hi,
> I have a ".app" file with "env" parameter for a certain application. When
> changed that and run the application in shell mode, changes are available
> the next run.
> But after I made the release, even though I change the .app file "env"
> parameter in the release directory, changes don't appear in the next run
> the release in embedded mode. To apply the changes what I am currently do
> re-create and re-install the release.
> Do .app parameters get cached in .boot or some other binary file?

Yes - that is correct. They are in the boot file. You can examine the
contents of the boot file as follows.

1> {ok, Bin} = file:read_file("myapp.boot").

2> io:format("~p~n", [binary_to_term(Bin)]).

> How can I
> change that without have to re-create and re-install the release?

Store your environment variables in a file called sys.config and
invoke your system with the -config flag.

erl -boot myapp.boot -config sys


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