[erlang-questions] Waiting for a node to start using run_erl

Yash Ganthe <>
Sat Jun 29 16:48:30 CEST 2013


My definition of "started" is that I am able to PING the node and get a PONG response back.

Thanks,
Yash

-----Original Message-----
From: Garrett Smith [mailto:] 
Sent: Saturday, June 29, 2013 7:43 PM
To: Yash Ganthe
Cc: 
Subject: Re: [erlang-questions] Waiting for a node to start using run_erl

What is "started" in this case?

A node start is a system startup, much like an OS start. There should be a point that you system is "ready" to server/act/etc. Once you establish that point, test for for it.

Just as an example of why this isn't always straight forward, consider a socket server (e.g. a web server). You might define "ready" as soon as the server is accepting connections on a port, which is easy to test for. But the server might in fact be ready several seconds later as database connections are opened, caches warmed, whatever. So a ready test might be a 200 response on a particular http request (which is able to test for all those conditions).

On Sat, Jun 29, 2013 at 8:42 AM, Yash Ganthe <> wrote:
> Hi,
>
>
>
> When staring an erl node using run_erl, if the -daemon switch is used, 
> control returns to the terminal immediately without letting me know 
> whether the node was really started.
>
> The switch is recommended in the documentation at:
> http://erlang.org/doc/man/run_erl.html
>
>
>
> It says: Without this option, run_erl must be started using several 
> tricks in the shell to detach it completely from the terminal in use 
> when starting it.
>
>
>
> Is there a way to use run_erl and ensure that the node is started. 
> This would be especially useful when starting the node from a shell 
> script using run_erl.
>
>
>
> Thanks,
>
> Yash
>
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