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| icimjs at loop.com |
 Posted: Mon Feb 08, 1999 9:43 pm |
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Guest
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Hi,
the mnesia manual says that erl should be started with
-config <path>
pointing at the directory in which the tables are stored. I'd rather set
that path programmatically. Can that be done? How?
TIA,
Elan
Post generated using Mail2Forum (http://m2f.sourceforge.net) |
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| ulf.wiger at etxb.ericsso |
| Posted: Tue Feb 09, 1999 6:58 am |
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Guest
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Elan wrote:
>
> Hi,
>
> the mnesia manual says that erl should be started with
> -config <path>
>
> pointing at the directory in which the tables are stored. I'd rather set
> that path programmatically. Can that be done? How?
>
> TIA,
>
> Elan
I believe that it's really -mnesia dir <Dir>
The 'dir' parameter can be set from the command line:
erl -name <Name> -mnesia dir <Dir>
or in a "config" file, which is identified with the parameter 'config'
erl -name <Name> -config <ConfFile>
For various reasons, the file should be named sys.config, and has the
following format:
[{AppName1, [{EnvVar, Val}]}].
For example:
[{mnesia, [{dir, "/home/joe/test/mnesia.n1"},
{embedded_mnemnosyne, false}]},
{kernel, [{start_ddll, true},
{start_disk_log, true}]}].
Setting the environment variables programmatically *can* be done, but
you have to use an internal function in the application_controller:
application_controller:set_env(AppName, Key, Value)
It is not recommended, and you will not find the function in any manual.
What I do is that I generate the sys.config file programmatically during
an installation phase. I don't think it's such a good idea to be
changing those variables in a running system anyway - better to create a
static configuration and then start the erlang node from it.
/Uffe
--
Ulf Wiger, Chief Designer AXD 301 <ulf.wiger_at_etxb.ericsson.se>
Ericsson Telecom AB tfn: +46 8 719 81 95
Varuv |
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| ulf.wiger at etxb.ericsso |
| Posted: Tue Feb 09, 1999 7:18 am |
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Guest
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Ulf Wiger wrote:
>
>
> Setting the environment variables programmatically *can* be done, but
> you have to use an internal function in the application_controller:
>
> application_controller:set_env(AppName, Key, Value)
>
> It is not recommended, and you will not find the function in any manual.
>
Ok, confession time. 
I *have* done this myself in production code:
patch_load_mnesia(Dir) ->
application:load(mnesia),
application_controller:set_env(mnesia, dir, Dir).
After this, you may issue application:start(mnesia).
I do this in an installation program, which also configures a start
command and a sys.config file. After that, all parameters are set
correctly every time the system is started.
However, there is also a function, mnesia:start(ExtraEnv), which does
the same thing. It is not official either, so I guess it's just a matter
of choosing your favourite undocumented feature and running with it. ;)
I still recommend messing with the env variables at installation only,
and not afterwards.
/Uffe
--
Ulf Wiger, Chief Designer AXD 301 <ulf.wiger_at_etxb.ericsson.se>
Ericsson Telecom AB tfn: +46 8 719 81 95
Varuv |
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