How do I specify a working directory for mnesia without resorting to passing the "dir" parameter on the command-line?
In other words, can I specify a "working directory" for mnesia just before calling `mnesia:start()' ?
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133answers:
2... just found it myself whilst browsing the source code of ejabberd... although they use `application_controller:set_env` instead. How wonder why?
jldupont
2009-12-03 20:08:54
There is an application_controller process started in Erlang VM. `application_controller:set_env` is the "API" to this process. `application:set_env` is a more abstract call, that just deals with applications. No wonder though that currently it only calls into that API.
Zed
2009-12-03 20:14:17
To answer the question :), I believe that the existence of application_controller server and module should be regarded as "implementation detail", and thus the proper way is to use the application module.
Zed
2009-12-03 20:20:42
@zed: agreed on your previous point.
jldupont
2009-12-04 13:43:23
+1
A:
Besides the method call mentioned in other responses here you can also specify this in a system configuration file or .app file specified with the -config parameter. See http://erlang.org/doc/design%5Fprinciples/applications.html#id2270704 for more information. This allows you keep the configuration seperate from the code and avoid a lot of command line flags.
Jeremy Wall
2009-12-04 03:23:20
I have a similar situation ... and I don't want to set mnesia dir from inside the code ... Can you please elaborate how .app file of an application should be used to set env variable for other application. I understand how this can be done using .config file though. e.g. My application file is test.app and it had mnesia listed in "applications" section, so mnesia is started automatically when I start "test". How can I pass "dir" value to mnesia using test.app?
spkhaira
2010-09-27 18:47:47
the relevant documentation for that is here: http://www.erlang.org/doc/man/app.html specifically the env tuple in the application file spec. anything you can set with set_env() can also be set there or on the commandline.
Jeremy Wall
2010-10-08 04:20:36