[erlang-questions] Autogenerating node names

David Sveningsson <>
Fri Dec 12 10:31:42 CET 2008


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Per Hedeland wrote:
> David Sveningsson <> wrote:
>> Thanks, but I was hoping to be able to skip the timer part. Does anyone
>> know when epmd forks? Before or after its initialization?
>>
>> Let me rephrase that, is epmd ready when "epmd -daemon" returns or must
>> one wait an unspecified time while it is starting?
> 
> I'd rephrase it as a suggestion, because it's a very nice way to
> start up a daemon, but epmd doesn't do that - it forks first
> (read the source:-). You can use erl_epmd:names/0 to check on
> its presence/readiness though, e.g. something like this:

You're right, I should have read the source. =)

> 
> start_epmd() ->
>     start_epmd(0, 10).
> 
> start_epmd(N, N) ->
>     {error, too_many_tries};
> start_epmd(M, N) ->
>     case erl_epmd:names() of
> 	{ok, _} ->
> 	    ok;
> 	_ when M == 0 ->
> 	    os:cmd("epmd -daemon"),
> 	    start_epmd(M+1, N);
> 	_ ->
> 	    timer:sleep(1),
> 	    start_epmd(M+1, N)
>     end.
> 
> Adjust "10" and "1" to taste, when I tried it I never managed to
> get to the sleep...
> 
> --Per Hedeland
> 
> 

Thanks, this works excellent!
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